Why do you think they need "one on one" time as opposed to "family time"? Why not try to build some good memories with all of the kids together (or at least a couple of them) ad opposed to just one on one? Would save you some more time for yourself, too.

Get up a family card game or board game (or Xbox, whatever) and have a mix tape playing with music you know everyone likes (or invite one or more to bring the music, or take turns)... Have fun snacks like popcorn or m&Ms available.

My S20 has Tourettes, which like Asperger's is considered by many docs to be on the high functioning end of the autism vspectrum, and shares some of the characteristics, and he always did better in group settings with his brother than he did one on one with us.

H53/W51, R-ing 4/'18

"Do not arouse or awaken love until it so desires"-Sg.of Sg 2:7

"So oftentimes it happens,that we live our lives in chains, & we never even know we have the key"-Eagles III 1:3