Hello,
1. Create a unitstat with is set to #/2 by script.
2. Create an exclusion group limited by a @unitstat.
3. Each option you need to be limited uses 1 on this exclusion group
Or
1. Create an exclusion group limited by #
2. Each option uses 2 on this exclusion group.
Note the second solution is easyer to implement, but it round down your division by 2.
If you need details on the implementation, just ask
Hope that help.
Frédéric