PT care and set days

I have always been very flexible with offering whatever days the clients wanted when they switched from FT to PT. I do have a 3 day a week minimum for PT kids(only offered to those over 2yrs) The problem is that a full time spot is being broken, and they are choosing days in the middle of the week. So essentially I can't fill the spot on the other days, and as well, they're avoiding mondays when most stats. fall, so I'm not getting the stat pay either(which all of my other clients pay for)
I'm thinking about mandating mon/wed/fri as my PT spot, so that I can compensate myself for the stats, as well as people looking in my area want either mon/wed/fri or tues/thurs, and then I could fill the tues/thurs if someone takes the mon/wed/fri first.
Do you mandate what PT days look like or offer whatever the clients want?
I have 3 pregnant parents who will all be due at the end the year, and I have a feeling they will all want to stay on for 4-6 months to keep their preschooler in, and choose days that avoid having to pay for stats. I don't want it to be a free for all, and me have 3 FT spots broken up and not able to fill them.
Thoughts please???Thanks!

I quit doing part-time all together. If you want the spot then you pay. I am not loosing money to do favors for clients. There is enough demand for full-time care I will just go onto the next family.

When I did do part-time I charged everyone stat pay regardless if it fell on their day or not.

I also no longer accept part time but when I did, they paid every other stat and then I changed it to every stat.

Because you've been so flexible, you can't blame them for doing this. However, if it's no longer working for you then you have every right to change it. Give them notice of the new policy and let them decide if they want to stay or go.

2 of the families could/should a ft spot

I do part time spots and I tell the parents what days m/w/f and then t/th so 2 part time spots fill one full time spot otherwise they will all try to avoid the Mons

I only take part-timers if they are current families who want to move to part time during mat leave and intend to return. I choose which days are available, and they decide if those days will work for them or not.

I don't take pt either cause I could never fill the days

I have one long term PT child but normally I stick to FT.

When I did allow PT it was for 2 of my places. Parent did contract for fixed day and no ability to swap. I never allowed PT client to have more benefit than FT client. If and only if, I had capacity for different day and parent needed switch, then they pay for that extra day.

I no longer allow parent drop part time in mat leave. Doing that mean loss of income for me. I cannot find temp client for days mat leave family not using and then kick out new client when mat leave end. That not fair. Here, if Mom pregnant and using full time place for current child, they either honour the ft place they contracted for, or leave and hope for two spaces when they need them. But I not taking loss of income for full year just to have child return to their contracted space since I not able promise space for babe anyway. It easier to fill FT place than PT days so I would prefer they just leave.