Whatever your opinion of Levi Johnston, he should be commended for fighting for joint custody of his son. Being wholly at the whim of the mother's family is risky for a noncustodial dad even under the friendliest of terms. And it's safe to say that, with Grandma Palin periodically indulging in adolescent mudslinging with Levi, terms are increasingly unfriendly.
Best for Tripp, and everyone else involved, if some legal parameters are set now, before relations get any uglier.