Rude, and Domineering MIL Wants To Sue Us For Grandparents Rights?

Ive asked a couple of questions about rude in-laws.My mother and sister-in-law want to take our children when me and my hubby are gone on our 7 day get away. We've told them NO on about 4 occions (because of different cirstances). Weve offered to pay for the trip (airfare and lodging) to come see the kids while were gone. My brother and his wife +their 3 kids are coming. My brother's mil might come as well (were paying for their rental car and gas). My mother and grandmother are coming as well. My mil got mad at me especially since my hubby laid it all out there for them. I send them pictures of the kids, and they talk on the phone with our eldest child. Weve NEVER denied her access to our children. Well NOW, she (my mil) is talking about getting a lawyer and seeking court appointed visitation in her home in a different state. Can she legally do this?