D&D is designed with the idea the the whole party can go through the checks multiple times. As Mat22 has said if Larian implements the whole party being available for conversations (which some UI elements are present, without having looking at any code I don't know about back-end elements for this) the issue goes away.
We currently do have Larian's homebrewed inspiration. Which works very well. If the player selects dialogue options that are "in-character" they get to re-roll future social skill checks.
So long-term I think this won't be an issue. The player can use the optimum character for the dialogue and will have a bank of inspiration re-rolls.
