Controlling an entire family actually sounds like an interesting idea. I think you should keep it in. If you don't want to use an "explore as group" option then don't. Just say the rest of the family has to stay in the house and you could even give them things to do while you explore. I know Mana Khemia had a bulletin board where you assigned jobs to party members to do during the week while you explored (though they seemed to do it on the side and came with you anyway), and one of the Alundra games (I think) had one character explore and the other make items with the components the explorer found.
Oh, then there was Legacy of the Wizard for the NES where you had an entire family that needed to explore a dungeon. Each member of the family had some bonus that you needed to exploit in order to explore one section of the dungeon, but you then had to leave the dungeon and go home so another person could explore the new area. (For example, the father did the most attack damage, the daughter jumped the highest, and the son was the only one who would wield some sword you needed to beat the boss.) I also think if one of the members died in the dungeon you couldn't use them again (permadeath), but I may be thinking of another game.
Those might be some ideas to consider.
