Does co-sleeping mean mom going to bed at 8pm???
The 8 year old is definitely old enough to have a conversation about his own bed. For the baby, I always had a place that he/she could sleep until I went to bed (moses basket, carrier, crib) and then we'd co-sleep the rest of the night. The moses basket and rolling bassinet were good because they were easy to move from room to room (don't carry a basket by the handles with a baby in it though!). The crib didn't work well for us until the baby was a good bit older, maybe 1 year or so. And even then, it was 2-3 hour solution for until I went to bed. If she's really clingy, keeping her asleep in a carrier until you're ready for bed is probably your best bet.