Why do you make it so complicated with block and unblock? When the condition in date X should not be posted so why is it inserted then? I mean, at date Y the billing team had to go to the contract again in both cases.
When you want to see the condition value for informational reasons already at date X, then I would insert the condition as statistical condition. So you can be for sure that it will not be posted. Of course you canot see any cashflow in the contract then, but in REISCDCF or in some custom programs you can ;-)
Regards
Michael