Since the last update the preset for the condition "if X mercs died in the last 14 days" doesn't work.
I already sent a bug report but it is not fixed yet so if you have your own created mercs react to such a situation it won't work and they will accept a contract or if they are already in the party they won't leave and will be rehireable aswell.
The problem is that when you set a 2+, the mod editor doesn't save the preset condition and keeps it to Zero.