usualsuspect -perhaps I didnt explain very well.
My point is that if the decision to use gp's for free childcare is driven by financial need (which many people have mentioned on here, the parents needing to keep a roof over their heads etc) then in a way, an enormous responsibility is put on the gp's from the word go. In this situation, presumably the parents discuss with the gp's first. After all, they aren't going to launch into having children if they can't afford it. So there must be a conversation along the lines of "We really want to have children, but we both need to carry on working and we can't afford childcare. Therefore we can only do it if you are willing to provide free childcare" (I'm sure such conversation would be more detailed, but I'm just giving the gist!) Automatically, the gp's are placed in a really tricky position, because it's almost as if the issue of the having children in the first place becomes the the gp's responsibility, not just the parents. How can they possibly say no? Even if they secretly harbour a desire to take off around the world, or go and live somewhere else, or even just have time to themselves, they are going to feel the weight of responsibility to provide that childcare. I don't think that's fair. And apart from anything else, what if the gps become ill, or frail, or unable to continue the care? It seems very unwise for parents to have children on the basis that they'll get looked after for free.
If on the other hand, the financial aspect isn;t an issue, then as I and many others have said, build a great relationship with the gp's, do lots together, have the close and loving relationship which can exist between gp's and grandchildren without expecting free childcare.