I hope Info-record is the first option for contract.
Suppose your info-record contain price 10..
And you are trying to create contract with price 5.
After first time when you enter the price 5, you will got a message
"Net price for item 00010 taken from conditions"
And the price get changed to 10.
After that you can change the price manually to 5.
I hope BAPI also contain the same.
I don't know much about BAPI.
But you can understand the logic to change the price.
I suggest Mark deletion flag for info record before run LSMW.