My niece and nephew lived one week with their mother and the other with their father. They live only a mile apart.
There were times that things (business trips) would come up and for whatever reason they might have to change days or swap etc.. but it worked. If a child REALLY missed a parent they were allowed to call them at any time and to request to see that parent.
When my niece was injured at school, she wanted her mom.. so that is who they called even though it was dads week. My sister called her ex on her way over to let him know what had happened.
The kids had their own bedrooms at both homes. They were not guest in either house. They had chores at each. They had their own clothing at both homes and there were not "dads clothes" and "moms clothes". They were the kids clothes to wear and take back and forth as they wanted.
They kept toothbrushes, shampoo, hair brushes,, etc at both homes, so they generally, were not lugging luggage all of the time. There were times they forgot something so they dealt with that..
The kids had sleepovers at each home, they had birthday parties at the different homes depending on how it fell on the calendar.
In the beginning my sister would bicker with her ex at pick ups and drop offs. She made it hard for the kids. They would cry and be so upset, And when her ex announced he would be remarrying.. she totally lost it. Even though, she is the one that had wanted the divorce in the first place..
This is when I told her she needed to not do this, to remember our childhood (it was just like the way our parents acted when we were children). She did not appreciate my opinions and that lead to her telling me to stay away from her and the kids. Thank goodness the kids father and second wife have been gracious about allowing me to see the kids,.
One thing to remember is that you have your way of doing things and he has his way. Your daughter will adapt. He is just as much her parent as you are.
I assume this sister will not be smoking pot or anything around your child.
And certainly never driving under the influence of anything when driving.
But if you are concerned just mention, "Is this babysitter the sister you told me smokes pot? " "I am sure you will speak with her about not smoking around daughter or driving her around if she is under the influence of anything. "
I know it is hard for you to not have your daughter all of the time and now every other week. The best thing to do is find something to do on your own. Exercise, join a book club, entertain friends, volunteer, or just enjoy some private time for yourself.