Hours changing, what do i do?

I currently have a child who I care for, she only comes one day a week at the moment (a Tuesday) mum has just taken a full time position at work, child's dad currently looks after her on a Monday so that will stay the same but nan has offered to have her one afternoon a week and then grandad one day a week. (Both nan and grandad won't be doing the same days or times ever they will just work round mum)

Mums new hours will be a 4 week period of different hours each day. Every day and week will be different but then those 4 weeks will stay the same every 4 weeks. The parent is currently charged an hourly rate of £4 per hour and this includes food etc, however mum has figured out the new price herself for 77.5 hours (per 4 weekly) at £310 a month (I charge for 47 weeks per year as I take 5 weeks holiday a year) I am sorry it's so confusing!

Basically I just want to know what I do as this little girl will be taking up a full time position as it isn't likely that I would find a child to fit in around her 4 week rota! Would u just charge her the hourly rate? Would you figure out a half or full day price and charge her that (if so how much?) or do I charge her for a full time position????

I really don't know what to do! And what makes the situation worse is that since looking after her daughter we have become really close and we go to each other's homes for wine etc so I don't want to be mean but I want to be professional In how I handle the situation!

Any comments or advice welcome :-)

I think it depends on how much you need the money.. Saw a thread recently where the
Minder charges a min 100
Hours a month for shift worker at maybe 1.5 times the hourly rate. They top up if it's more than that. I never did shift before but have worked out what I expect my monthly income to be and divided it by 3, so this is the figure each child or space needs to bring in then I divided it by 100 for the hourly rate. Don't know if this would work for you? Otherwise can u fill around it with ad hoc care? It's a difficult one!

Reading these really confuse me lol I just charge hourly to everyone the only difference in price is with age but I see where your coming from I have a boy that I have 4 hours a day 4 days a week. Those days are different every week and the timing different every day I just find out the week before and I do find myself saying no to some mums even people that only want 3hours in the morning, because I don't know when I will have this boy! I would defo add a bit on!

So parent will need 77.5 hours of care per month
I would then work out how many hours she would actually need me to hold a space for her and charge half fees for those

I.e.
So if the total hours required were 150
77.5 hours of actual care at full fees, Plus 72.5 hours at half fees