It should be possible to combine multiple percentage-based promotions/discounts, but a total maximum percentage value can be defined, so that, for example, no more than 50% discount can be applied in total.

For example:

10% + 10% + 10% + 10% + 10%
or
20% + 30%
or
5% + 15% + 30%

So that, for example, an employee promotion (Corparate Benefifts) can be combined with a birthday voucher and a newsletter registration.

Currently, you have to exclude many promotions per promotion for each individual promotion that you create but want to restrict the combination. Defining the whole thing on the basis of the percentage value would only be a single definition of a maximum value.