I don't know why, but buying from collection files is banned on dormitory lots. I can't give my YA sims living in dorms traits because of this. Has anyone ever made a mod to correct this error?

No, I don't think a mod has ever addresses this.

Have you tried using the building tool cheats? Would that make collections accessible? (boolProp dormSpecificToolsDisabled false)

Otherwise, you could summon them to another lot and give them traits, or, if you use a build/buy enabler, go to a community lot and use buy/build mode there. I think collections should be available then.

Have you tried making the collection on a dorm lot to begin with? As I have definitely used collections from dorms before.

I don't use traits though so maybe I'm not understanding why this is relevant.

I believe the OP has the traits in a collections only bundle, so they only show up in the collection, and don't clutter the catalog. But certain build features are not available in dorms, and I believe collections is one of them. But perhaps it depends on the type of collection?

Yes. I play 3t2 traits and I don’t want them to show up anywhere except a collection file.

Use a build and buy enabler- I wouldn't play without it.
https://modthesims.info/d/204467/bu...r-for-pets.html Go to the comments and you will find the updated file, roundabout post 48. The pet file won't work in the full game.

Build mode is available in dorms and everywhere thanks to the uni cheat code boolProp dormSpecificToolsDisabled [true/false]

If you add these lines to your userstartup.cheat file, you won't have to type this long code, just toolson or toolsoff:

alias toolson "boolprop dormspecifictoolsdisabled off" "tools accessible" "dormspecifictoolsdisabled off"

alias toolsoff "boolprop dormspecifictoolsdisabled on" "tools off" "dormspecifictoolsdisabled on"