As stated, this mod is just a combination of configuration files using Base Object Swapper  and Seasons of Skyrim SKSE to integrate Fabled Forests, Traverse the Ulvenwald and Veydogolt Trees.

Why did I do it ?
Simple, I was just testing tree mods, Traverse the Ulvenwald, while great, lacked some of the awe induced by the bigger trees with dense coverage of fabled forest, at that time I tested both veydoglot and fabled forests and was instantly surprised, but there was an issue. Veydoglot trees does not provide seasonal variations for aspen trees nor reach trees, which means in summer these trees keep the autumn look, which left me unsatisfied. 

I decided to tackle the problem and decided to use the base object swapper version of veydoglot trees to better account for that, hence I started researching how to properly manage the issue, and I stumbled upon Fabled Forests - Ulvenwald - Compatibility Patch (BOS), which provided the necessary inspiration. Variety.

Hence I decided to build these configuration files.

What it is exactly ?

This mod is a set of configuration files based on different combinations, and can be mixed and match according to preference. Also the user is encouraged to tweak the values if needed.

I Fabled Forest + Veydogolt Trees: 4 possible combinations

1- Fabled Forest + Veydogolt trees (regular): No need for configurations from this mod. Load Veydogolt trees after fabled forest and let it overwrite. All trees from fabled forest placements and proportions but with the models from veydogolt trees.  CON: Inconsistencies with aspen trees and reach trees with seasons of skyrim, because it will use Fabled forest models for summer and spring which are different from veydogolt models.

2- Fabled Forest + Veydogolt trees (BOS): Needs season configuration from this mod. No restrictions for mod order, or load order. This will solve the inconsistencies for tree models, but summer and spring will use autum trees.

3- Fabled Forest + Veydogolt trees (BOS) + Custom Swap: Use a modified SWAP file from veydogolt trees only replaces some of the trees from fabled forest with trees from veydogolt trees for added variety. Aspen and reach trees are replaced with in a lesser percentage (30%) to give priority to fabled forest variants which have 4 season variants 

4- Fabled Forest + Veydogolt trees (BOS) + Custom Swap - No Aspen: Use a modified SWAP file from veydogolt trees only replaces some of the trees
from fabled forest with trees from veydogolt trees for added variety. Aspen and reach trees are not changed from fabled forest for maximum consistency across seasons


II Fabled Forest + Traverse the Ulvenwald (Compatibility):  This is basically the same idea behind Fabled Forests - Ulvenwald - Compatibility Patch (BOS), but this is my version, which is a slightly different strategy (to build the ini). In short it removes the conflicting trees (~3000) that are added from both mods at the same time. 2 Possibilities:

1- Keep Ulvenwald trees:
2- Keep Fabled Forest trees:

Chose whichever version you would prefer. The effect should be the same as inFabled Forests - Ulvenwald - Compatibility Patch (BOS), but I like my version better (Without Aqiriza documentation, I couldn't have built this version).


Installation and Load Order ?

These are just configuration files, so the only concern is related to the requirements. I use MO2, so vortex users need to adapt accordingly.
1- Install Traverse the Ulvenwald (Optional)
2- Install Fabled Forest (required)
3- Install Veydogolt trees , BOS version (optional)

We want to install Ulvenwald before Fabled forest because we want the default tree meshes and textures to come from Fabled Forests.

Veydoglot trees BOS, can be loaded wherever, just let loot sort it.
Load Fabled Forest  AFTER Traverse the Ulvenwald,

We need Fabled Forest to load after traverse the ulvenwald for 2 reasons:
1- We want the size edits from fabled forest to win
2- Ulvenwald changes the tree Ids, which breaks the BOS configuration for Veydogolt swaps.

So if you don't care for veydogolt trees and want to keep the default trees from ulvenwald, then you can load ulvenwald after.


So Why not just use the other compatibility patch?

There are 2 reasons:
1- Number of duplications: My version fixes almost 3000 duplicated records, while the original only finds about 1200
2- How the conflicts are solved: The original solves the conflicts by moving the trees 3000 under the soil and setting them as initially disabled. This mod imitates Lightened Skyrim - Base Object Swapper edition by just swapping the object with a void object.


And how did you magically find ~3k conflicts ?

Because the process is a bit different, and in my opinion easier to perform and follow (a good text editor is greatly recommended).
1- I opened SSSedit for ulvenwald and fabled forest.
2- Apply the find conflicts for these 2 mods only.
3-  use  Copy Records to Clipboard - xEdit Script. to copy the world records conflicts to a new file: conflicts.ini
4- Copy all world record additions from Fabled forests, and traverse the ulvenwald  to a new file fabled_all.ini and ulvenwald_all.ini
5- Remove the references to esp/esm from the files (0xFC29~Ulvenwald.esp -> 0xFC29~) and sort the lines
6- remove all conflicts from fabled_all and ulvenwald_ini to create the new files fabled_unconflicted.ini and ulvenwald_unconflicted.ini respectively
7- Use ulvenwald_unconflicted to remove all from fabled_unconflicted that exist in both files. This will give fabled_only. Reverse the roles to get Ulvenwald_only.
8- Use ulvenwald_only to remove all lines from ulvenwald_unconflicted that exists in both files, this will give you ulvenwald_swaps.ini. Repeat for fabled_forest to get fabled_swaps.ini.
8.1 - (optional) Inspect the file for duplicates
9- Finish the files with the proper syntax (0xFC29~ -> 0xFC29~Ulvenwald.esp|0x3B~Skyrim.esm)

If everything is correct both fabled_swaps and ulvenwald_swaps should have the same number of lines.


Any missing conflict (2 trees that overlap or occupy the same space but have different IDs, have to be found and fixed manually), during my testing I only found one, but there may be more.
To fix those, I use Console Commands Extender - Anniversary Edition Update, to ensure that I have highlighted both conflicting trees independently and note the ref_id.
Add the ref ids to the files. For further confirmation SSSedit/CK


Final Words ?

Performance: I didn't notice much impact in FPS. There is obviously a bigger impact on VRAM due to using More trees, more variations from veydogolt, fabled forest and traverse the ulvenwald.
Screenshots were taken with Raid Weathers and Community shaders. Fantasia landscapes was also used, but is not highlighted in the screenshots.
The screenshots are from Riverwood and Shor's Stone