Good luck then, @Aunza!
I think:
if you have all installed items batched on store pages as owned (me and some of my friends we have had problems with it, however items resulted in PH as part of sets);
if you have downloaded and installed items in small groups (under 200MB) in fabbric clean folder;
if some of installed Sims3Packs wasn't corrupted
and if you self haven't uninstalled items from it with launcher manually
.... launcher should make "good boy" and keep all yours store-content installed. ;)
(I have had this time success, but I've made multiple backups of DCBackup, DCCache, Library and InstalledWorlds - so I don't have to re-install again until (if this comes sometime) next store patch).
P.S.: More hard work on here is putting Valgon, I'm searching only help him here only, because I find his idea of quick download-links genial.
