It may sometimes occur that when you want to replace the Alchemy lab with the Children's room or buy the Childrens room right away, you get the dialog option from Proventus

...Buy Children's room blah blah... [...]Gold

This mod will not fix the dialog option itself but makes the Children's room available right away, so you won't have to bother purchasing it anymore.
The game does recognize that you own the room (regarding adoptions).

You only have to do one more thing:

1. Open console
2. Tyoe "prid e4ec8" (w/o quotation marks)
3. Press Enter
4. Open console
5. Type disable
6. Press Enter

That removes the spiderwebs etc. in the area.

It's nothing special but I thought I'd share it anyway :)