My dd was almost 3 when my triplets were born. How old is your son? Whenever my dh or I ran out of the house to do errands or get take out, we'd always take her with us. I would try to spend time with her everyday away from the babies, by just going into another room to read books etc. when my dh would get home from work, I'd take her outside to play, just the two of us for a little while. It will become easier when your babies are a little older & more predictable when they want to nurse, that you can find that chunk of time for your son. I had a mother's helper come in the afternoon & once my babes were nursed a lot of times I'd go take a nap with my dd or we could go into another room & do puzzles etc. like I said above. (I don't know if this is an option for you or not) We also would have popcorn nights maybe twice a month where once i had my three to sleep, my dd & I would watch a movie & eat popcorn-she loved that! Once my babes were about 7 months old i could get them napping together for about an hour in the am & hour & 1/2 in the afternoon, so we got even more time then. I always nursed my three down to sleep but didn't stay in their room for their nap, because of my dd. She has done great. Hang in there!
Beth Mom to Megan(almost 5), Rachel, Zach, & Ashley-25 months