We seem to be stuck in the old ways, where family was not just the nuclear, but where others within the family network were classed as an important in the social fabric.
I had also so many "Aunties and Uncles" that were cherished by our family. So much knowledge and cultural richness that were openly shared.
Children that are able to be cared for lovingly by GPs over a group childcare situation were the winners. They can still have play dates and attend Playgroup etc.
Our first was in QCWA, a family like setting, until we moved and the next one I would collect our daughter always in tears (one day I discovered why and she was removed), then GPs arrived, they both had their grandparents, where I could trust them to always care for our children. They learnt to knit, sew, swim etc under their guidance. Go for camps and sleep overs, so hubby and I could catch up with each other, have date nights etc. For 3 months of the year GPs went away on their own too, for their own R&R, it was a good, healthy arrangement.
These days, the extended family has been replaced by strangers, mentorship from Elders is being lost, kids often seem to be loosing the basic moral fabric we once all treasured and now some are turning to delinquency and who gets the blame? Usually kids that have lost their way due to the loss of the above.
Stay passive with your approach to your son and DIL, let them know you are there and hopefully all those months you kept their child safe and loved will be remembered and something positive come out of all of this for.