Hey Tan, My first DS Jack slept over a bit at his Grandparents when he was about 6 months old, when we had things to go to that finished quite late. And they were fine. Until Pa had a heart attack when Jack was about 10 months old, and since then I haven't felt right letting him sleep over yet..
But just the other week they brought it up again and he slept over, and they all had a ball!!!
And he is staying over there 2moro night too!! It is sooo cute because he sleeps in the middle of them!!
And Nick and I were ok, just wondering how they were and I woke up with every little sound too!!

So glad to hear you guys are letting your mum have Izzy for a sleepover. They will both love it!! Just try to enjoy your night out and your sleep in!!
I still have Toby to get up to in the morn, so no sleep in for me!!

And I think it is lovely for the grandparents to spend that special time with their grandchildren.. And I bet when gumnut comes along, you'll love Izzy to have a sleepover!!