It's been a while since I last played BG1, and I do know that if you have both Dynaheir and Minsc in your party the only way to separate them is to get one of them killed or lock them in a room, but what happens if you pick up D. without ever talking to Minsc in Nashkel? Is it possible to keep her W/O Minsc this way? I'm playing BGTutu with BG1NPC installed, although I don't think this should make any difference in this matter.
Yes, it perfectly acceptable to keep her without talking to Minsc, but... if I remember correctly, in TuTu, if you get close to Minsc with Dynaheir in your party, he will approach and force dialog Dynaheir out of your party, so stay WELL away from him. What I normally do, if I want Dynaheir without Minsc, is to pick her up and then drop her off somewhere temporarily -- I usually drop my NPCs at the Friendly Arm Inn for convenience, except for Jaheira and Khalid, who will leave under certain circumstances if you drop them off (it's a broken FAI script). Anyway, back to the point: once you've dropped Dynaheir off, pick up Minsc and drop him off somewhere safe, where you're never going back, then return for Dynaheir.