DD needs a very, very short WD -like only 5 mins before going in cot- we draw curtains, read a short story, play a short lullaby then put her in sleeping bag and put white noise on, she settles to sleep really quickly usually (within 5mins)
DS needed a much longer wind down before nap & bed- about 30 min before nap & an hour before bed. I had to take him away from v stimulating toys and environments and do quiet time before WD e.g, carrying him around, quiet toys (no lights & electronic music) then start a similar WD to DD's above around 20 min before nap & allow at least 10-15 min for settling to sleep.
If your DS2 is easily OS, you may need a longer WD. Tricky with DS1 around but maybe carrying in sling as part of WD without letting him sleep there might help?