I'm a 27-year-old woman living with my boyfriend, who is 27, and his family. However, his brother is creating some difficulties, and I'm unsure how to handle the situation.

I’m a 27-year-old woman living with my 27-year-old boyfriend and his family. Although our move to a bigger room in the house isn’t fully official yet, we’re currently waiting for furniture to be delivered and making adjustments to ensure the space is comfortable for both of us. Since September, I’ve been staying in his current room, gradually making small changes to prepare for the transition. For about six years, I parked on the street, but right before winter, my boyfriend reorganized the garage to accommodate my Honda Fit. With four other cars in the household, mine became the fifth. Now we can fit two cars in the garage and three on the driveway. I park in the garage alongside his mom, while my boyfriend, his dad, and his brother use the driveway. Recently, my boyfriend injured his hand and is currently unable to work, yet we’ve stuck with our routine. However, it’s become apparent that his brother often sleeps in late, causing delays for me as I try to leave for work. To remedy this, my boyfriend moved his car to the garage to ensure I can depart on time. About a year ago, my boyfriend’s brother started dating a lovely girl whom I get along with well. A couple of weeks ago, after playing DND with friends, my boyfriend informed me that his brother’s girlfriend parked in the driveway, taking up my spot. He was upset about this since I’ve transitioned from street parking to driveway/garage parking over the past few months. To avoid conflict while they were sleeping, I opted to stay at my parents’ house for the night because I didn’t want to imply that parking spots operate on a “first come, first served” basis. The real issue arose last night when I had a late doctor’s appointment and returned home around 8 PM. I parked in the driveway without thinking twice about it. After assisting my boyfriend with changing his bandages, his mom came in with some news: his brother had instructed his girlfriend to park in the driveway again. To avoid involving my boyfriend, who was asleep after a long day at the hospital, his mom approached his brother about moving the car. Unfortunately, the exchange turned heated; he reacted angrily, claiming it wasn’t a big deal and that I should just park on the street. He insisted that his mom was yelling at him, despite her calm approach. In defense of my parking situation, she stated, “This is OP’s home; you wouldn’t ask your brother or dad to park on the street, and your girlfriend doesn’t live here.” While he eventually moved the car, he continued to complain and argue with their mom, trying to guilt her into feeling bad. Now, I’m unsure how to navigate this situation, as I’m concerned it might negatively affect my relationship with his brother, particularly since my boyfriend values family ties.