You can specify property groups and subgroups for different customization elements of the same element. That element will have groups and subgroups from all customization elements.
Example
Let’s say we have two customizations of the same element type, the actor. The first customization has the property group My Group with the subgroup Subgroup 1 containing the property Prop 1 . The second customization has the same property group with the same subgroup specified, but the subgroup Subgroup 1 contains the property Prop 2 .
As a result, the actor element type will have My Group, with Subgroup 1 containing both Prop 1 and Prop 2.