Bose, I think where your assumptions and mine differ, is that you are assumming the airline pilot wishes to have a single pilot mutli rating, while I'm assuming they want to fly SEP's.
In my case they would be renewing their Mulit pilot IR and MEP in one go. Neither of which would sort them out for single pilot IR.
dp
Sorry mate you still have it wrong. The number of PISTON aircraft that require two crew these days is so small I could count on a finger (or 2 at most). Multi pilot IR's are renewed only on the type being flown which is subject to a type rating.
An MEP rating has is renewed annually by test. I renew mine at the same time as my IR.
You can't renew an MEP while renewing a multi crew IR unless that is a multi crew MEP and as DFC points out the only people flying those these days are Atlantic and its only a couple of them.