Barbara, to go back to your original question, <Hi, sometimes I get a message in RED that says something like: Caution, these profiles are in different trees, merging them may result in merging of more duplicate profiles>--
This is the message that shows at the bottom of the "compare profiles" view (commonly known as the carousel) when one of the profiles is not currently in the Big Tree. It is a warning so that you are aware that if you say "Yes, Merge" that you are sending a merge request to a manager non-connected to the Big Tree.
Be aware that curators are NOT able to merge profiles from such non-connected trees; we are only able to merge duplicate public profiles that are both attached to the Big Tree.
Rather than sending a merge request in this way, it is best to write a personal message to the manager of the non-connected tree and ask him or her if she is willing to join the Big Tree, explaining that once one profile is merged into the tree then all the profiles will need to become part of the Big Tree.
Once that manager understands the process and the implications, if she/he makes a decision to join the tree, that's great--but I recommend NOT bombarding them with merge requests without any prior explanation and agreement.