I took up finishing a Minutemen quest, during the quest "Taking Independence" I fast traveled after clearing the courtyard to get my power suit to defeat the boss (The Big Ass Mutated Lobster Queen). I had my dog going into the mission (possibly try more characters instead before starting mission), now I have both Preston and dog w/ me. Mission is incomplete but you can always go do it later (High Chance of losing Preston I'm guessing).