Perm Order?

For years 2 years now I have been the primary care giver of my 2 children. I have them about 80% of the time and do EVERYTHING for them.I get ZERO child support bc my X wife supposedly has no $$$. This past summer, my temp court order “rolled” to permanant after it being in place for over a year(Although the children have been living with me for a longer time due to their mothers issues). NOW, my X has been kicked out of her boyfriends house and is living with her parents and has decided that she now wants the kids 2 days per wk rather than her 1(which she rarely took advantage of anyway), I told her that if the children wanted to see her an extra day and we all agreed upon it that it would be okay but I was NOT going to permanantly agree to 2 day’s per week, considering the on going unstability of her life at this time. So, my question is…how hard/easy will it be for her to take me to court for her to get an extra day of visitation court ordered? Can she even do this and if so what does she have to prove/show?

In order to change custody she will have to show that there has been a substantial change in circumstances affecting the well being of the children which has occurred since the entry of the last order.