I don’t have DC myself so have never needed to call on my parents for childcare but the closest I’ve come to blurring boundaries was a few years back when I asked my recently retired Mum if she’d be interested in cleaning my house.
We agreed £400 for a one off deep clean for the Spring and then £200 monthly for a fortnightly visit to do a maintenance clean. We agreed that the £200 would also cover a specific ‘extra’ task once a month/every other visit: e.g. normal cleaning tasks would be things like sweeping, hoovering and dusting, whilst the ‘extra’ tasks would be things like cleaning the windows or cleaning the kitchen cupboards/fridge/oven/extractor hood etc.
My Mum lasted all of 2 weeks and 3 visits before she resigned, having deep cleaned the rooms upstairs, the living room and getting halfway through the kitchen. We have 3 large dogs that constantly shed a lot of fur, plus a back garden that, thanks to their crazy zoomies and North West England’s delightful penchant towards dampness, has turned my once pristine lawn into a mud pit. Essentially, she became quickly disheartened with the amount of dog hair and dust she had to tackle before she could even start any meaningful cleaning, and she felt whatever progress she’d made during the visit before was lost by the time she came back for her next visit 4-5 days later.
To be clear, my DH and I were doing our usual tidying up/cleaning in between her visits (we aren’t scruffbags!!), but with us both working FT, plus my PT studying for my Masters, we were always on the losing side of the constant, unavoidable, unassuaging battle against the tidal wave of dog hair and dust. It left her feeling it would be a thankless task and any outcome she did achieve would never be quite up to her (self admittedly) perfectionist cleaning standards.
In the end, after thanking her and paying her for the time she’d spent, we hired a local cleaning company to finish off the remaining bits of the deep clean and to do the ongoing regular cleans.
Of course it would have been lovely if it had worked out with my Mum - for her some extra money, for me having someone I trust implicitly to be in my home and to do a great and thorough job, not to mention the bonus of her and the dogs getting to spend some regular time with each other.
I don’t feel at all annoyed at her deciding it wasn’t feasible to continue and I’m glad she made the call to pull the plug as quickly as she did. Our relationship is far too important to risk over an arrangement that isn’t workable and the remotest chance of any slow building resentment forming (on either/both sides).
As it stands, I’m much more comfortable having a simple, loving Mother/Daughter relationship with my Mum and a separate, purely professional dynamic with the person who is toilet ducking my loo!
Perhaps you could approach the conversation with your Mum on the premise that given your DD is coming toward the end of her first year in school, you and your DH have been reflecting on current and future household arrangements (respective working set ups, split of domestic chores, quality of and availability for family time, childcare arrangements etc), and you’ve decided it would work best if DD went into wraparound care on x days each week (or whatever you think will be best for you), which means the focus of the time your Mum spends with her granddaughter can be less about providing regular/routine care and more on spending purposeful fun/quality time together, bonding and further growing their relationship?