OS=Outfit Studio
BS=BodySlide
TWB=True Wasteland Body

Step 1- Open BS and select an outfit or body you want to add sliders to.
Example=CBBEBody (the nude body that comes with cbbe)
Step 2- Click the small icon button next to the outfit list ( opens current outfit/body in OS)
Now you will see OS in all its glory.  Upper right of the program you will see a box with all of the parts in the current outfit you loaded listed.
Example= CBBE body will be all you will see, the box will simply say CBBE and it will be highlighted green.  This indicates it is the reference body of the outfit.
Step 3- Select and right click the green highlighted reference body and in the popup menu select Set Reference.
Example= Select and right click CBBE and the select Set Reference.  CBBE will now be grey instead of green.  That means it is not the reference body now.
Step 4- Go to upper left corner of the screen, select file menu, then select Load Reference, a  menu box will pop up, toggle the button next to From Template.  Select the reference you want to use, and check the two boxes at the bottom under Merge.  Be sure Zaps and Sliders both have check marks beside them.
Click ok.
Example= We will add my sliders to CBBE so select Rippedref from the dropdown menu. Be sure the boxes under merge are checked.
Step 5-  Now you will see the reference template at the bottom of the list in the upper right quadrant.  This is the point where you have some options when converting an outfit.  You can cntrl+click to select certain parts and the old reference body, or conform the whole outfit.  Whatever parts you conform will now move with the new sliders.  (You may be working with an outfit with several parts, lets say it has armor plates on the legs, you may not want the armor to deform and mold to the leg muscles so don't select those parts.)
Go to the upper left of the program and click Slider, then click Conform All if you wish to conform the whole outfit or conform selected if you picked out certain parts to conform.
Example= Click on Slider, and select conform all, since all we have is the cbbe body to add sliders to.  You will always conform the original reference body.
Step 6-  Now right click the reference template you loaded into the upper right quadrant and select Delete.  Right click the original reference body and select Set Reference. Make sure it is highlighted green again.
Example= Right click Rippedref and Delete.  Right click CBBE and Set Reference.
That's it the project is converted and will now use the new sliders.  The bottom left quadrant has all the sliders in it.  The new sliders will be at the bottom of the list. You can try them out and check for clipping with the outfit.
Step 7-  Go to file and select save and the new outfit will overwrite the old BS file or you can Save As and rename it.
Close OS and then close and restart BS.  The new BS file won't take effect until you either swap outfits in BS or exit restart.  My BS sometimes freezes when I swap outfits or won't reset, so I always just close and restart.

You can use this method for adding any reference template to an outfit or body, TWB, Uniboob, Lazman's Muscle Mania.

P.S.  English is my first language, I'm just bad at it.