Good news:
it is possible to add old (v2) Keyscape and Trilian into Omnisphere V3.
If you have STEAM folder (contain folder Omnisphere - and free space on disk) simply copy folders of old STEAM folder into new one. Then new STEAM folder will contain three folders - Keyscape, Omnisphere and Trilian. Each of it contains the same structure (Defaults, Documentation, Settings Library and Soundsources).
If you don't have enough space, simply cretae symbolic links to Trilian and Keyscape folders, move it to new STEAM folder. Name must be the same as in old STEAM folder, not like „Keyscape symlik“.
Bad news:
Some of sounds don't play (e.g. PRS guitar), for now I don't why.
It is not possible create „copy“ of old Omnisphere library beside new, like Keyscape or Trilian. I try it by rename old library to Omnisphere 2 and put into STEAM, but app don't see it.

how do u deal w all the steam files being separated?