I mean, letting Lyvia train the mercs at the cost a valuable party member is reasonable for now. Some choices need to have consequences after all.
Frank training the mercs is a good idea, but maybe with a bit of penalty could be an interesting gameplay choices.
- Lyvia's training takes 3-4 days to complete, but she won't be available for your team.
- Frank's training takes 6-7 days to complete, but Lyvia will still be in your team.
Now you gotta weigh the pros and cons before deciding which one is the best for you.