Yes, if the homes are at the same path. You could work around this.
Okay I think I understood: You have homes that are "marked via the apple generated UID" for a specific user and you want to create a new UCS user that has the same mark and then just uses the old folder so you have less hassle with the migration. I do not think that is possible - that would a patchwork-solution even in a LDAP to LDAP area. In my opinion, it would be way safer and much easier to just backup the homes and restore them in the newly created homefolders.
I am sorry I cannot help with your idea.
I think there is a misconception here. Open Directory is not the same as OpenLDAP. OpenLDap is used in UCS, Open Directory is the "Apple Open Directory" implementation. The used attributes and migration ways can differ quite massivly. The helpful information in this specific case would be: do not do it - do it easier and reliable.