Hey Frosty! :D Everything's pretty open because I want to keep things flexible for potential storyline partners!
For the girlfriend, I would like someone in their 30s for sure, but I have no face in mind! The only other stuff I have about her is that she'd have to live in New York and that the relationship isn't doing so great currently. I'm sure them both having dead family members and going on this trip isn't helping the situation. This could lead to a potential break-up or big reconciliation, depending on how things play out! I'm definitely not looking for his significant other to be a villain or anything like that. I'm just very into people who care about each other having rough patches and/or growing apart, haha.
For the sister, someone college-age, probably brunette to be safe. An academic star, putting her in contrast with Brand who was an average student at best. Their parents like to rub that in his face a lot, but he never held it against his sister. He took her to baseball games a lot when she was growing up.