I never flush mine. Last year I scanned 194% 5 singles.4 trips and the rest twins.
All the trips brought the 3 and I let them get on with it and all lambs are now undetectable from the rest. They have loads of milk and can carry 3 ok.
Tales of multi births are mainly hearsay and as for flighty mine all gather around me when I walk up to them.
If your getting any sheep try to get them from a smallish flock that have been handled.
Lleyns will find a ready market anywhere in the UK.