Like many, my #1 request is to remove the chained/unchanged portraits system (auto-follow) and replace it by the good old, universally approved, simple system of "Select character(s) 1 | 2 |3 | 4 | Pet A | Pet B" or "Select all" to move those characters/creatures. Usually games offer a hotkey to select all if what we want is for every character to move together.
In the case you mention (OP), selecting your caster should have only her/him move and cast. Simple enough.
The old system, which I endured all of DoS1, should rest.
Larian has not responded to this popular / common sense request.
Last edited by Baraz; 26/02/21 06:36 AM. Reason: Fixed syntax error and improved my message all around.