Well, I understand the urge to stay in contact with past play partners, but as a part-time domme, I also understand the need to feel like your sub is yours (unless you have some other arrangement). I think the best thing to do would be for all involved to be in equal contact with said past partners, not just the person who was formerly the sub. Could be informitive for the current dom/me too.

Naturally, that's just what worked for us. May not be the best thing for every couple. YMMV