Wannabe,
You are confusing Cooperative Assignments and Sandwich Leases.
QUOTE
In the manual Michael say's that he doesn't bother the seller with giving rent credits this has me a little confused.
When doing a Sandwich Lease, don't worry about Rent Credits from the seller. You are in the middle of the deal. Your goal is to get to the seller's bottom line -- as low as you can get them to go, both monthly and option price. This in no way affects whether or not you give your tenant/buyer's Rent Credits -- one deal with the seller and another separate deal with your tenant/buyer.
QUOTE
I understand that rent credits are a big insentive for the T/B to pay his rent on time. so do I explain to the seller that after the contracts are assigned he will be responsible for keeping records and giving the T/B a credit for each rent payment which is made on time?
Don't make it seem like a chore. When dealing with a seller on a CA, explain the benefits of Rent Credits -- find a tenant/buyer quicker, major incentive to pay on time, won't alter the NET you'd already discussed with them, etc.