If I understand you correctly, Yes.
I have 4 accounts with houses currently. Main account owns a keep, all other accounts are co-owned to the keep. Account 2 Owns an 18x18 I turned into a public park, other 3 accoutns are co-owned. Account 3 owns a vendor house, all other accounts are co-owned, account 4 is holding a junk house i'd like to sell someday because its in a nice location, main account is co-owned.
All new co-owner features work properly etc. No issues with decay etc.