The transfer rules have never had any relationship to common sense. Current rules are more relaxed than old rules (in other words, the trend has been to make it easier to transfer). Old rule was you could transfer only current points, transfered points could not be banked, and you could do only one transfer per use year (either in or out but not both). New rules: still can only transfer current points, recipient can now bank the transfered points, you can transfer out as many times as you want in any given use year or transfer in as many times as you want in any given year, but you cannot both transfer out and in for the same contract and use year. Logic to the restrictions? There is none other than the restrictions help to discourage transfers and MS avoids having to deal with more of them.
When you have two different contracts it is generally easy to avoid doing more than one transfer when you do a trip. You make your reservation for some of the days of your trip with one contract and make reservation for other days with the other contract. At most you will then have one odd day where neither contract has enough points for it and you do a transfer to cover that odd day. You then link the reservations together so that they all become one for the purpose of MS accounting and staying in one room. Also, as noted above, MS tends to be more flexible about allowing transfers when it is just a member transfering between the member's own contracts. (That might have to do with the ambiguity in the offical documents that states the transfer restrictions are applicable to transfers between "members" rather than between "contracts" and thus there exists the question as to whether any of the retrictions even apply to a member transfering between his own contracts.)
