Family of origin moving to my state, and I'm not happy.

Hi, throwaway account, but 1st post on Reddit.

I was parentified as the oldest daughter and had to take care of my younger siblings (we don't have the same dad, and my mother was a single parent). All typical "eldest daughter syndrome" associations apply here - problem solver, over functioning, financial pillar, independence, etc.

When I was 18, I went to college and essentially never moved back home. I couldn't wait to get away and be free. I have always lived in different cities or states from my family of origin - anywhere from 1.5hr drive away, to a 5 hr plane ride away.

I have now moved to a popular state/city for the past year, and my younger sibling (by over 15 years) is now planning to relocate here. They have mentioned that they are going to need "their village" when they get here. My husband and I have no children. My sibling and their spouse have a <1 yo, and a tween.

My sibling has also already preemptively asked if they can stay for a week or two and look for their rental apt/home in advance of the move. Since my sibling lives close to my mother, my mother is saying that if this sibling leaves, my mother is relocating here also, so that she's not left alone.

My mother is a senior who still works and has no retirement. She also has an active mortgage. Despite the abuse and povery from my childhood, I currently pay smaller monthly bills for my mother and pay for ad hoc needs (appliances, emergencies, etc...always in the thousands). I feel that if they move locally they will have expectations that I'm now part of their LOCAL "ecosystem " and will be available for assistance.

I'm concerned about how their move will encroach on the life my husband and I have built for ourselves. Also, I prefer my family in small doses. We have different mindsets, tolerance for drama, emergencies, etc. I worked hard, and continue to do so, for the peace, happiness and STABILITY in my life that my childhood didn't provide.

I think my sibling is going to expect babysitting, since I'm the only person/family they know here...aka "the village". Adding to that, my husband and I have a 4br home and are high (1%) earners (the highest in both our families, although they don't know how much we make). Am I overthinking this or is the expectation for constant assistance the likely read here? Maybe I'm not giving them enough credit, but I feel the writing is on the wall.

Thank you for reading this.