Assign common grouping to multiple overlapping area

Hi @egomm, this workflow might help you.

1. AttributeExposer: Expose "Group".
2. AttributeManager or AttributeCreator: Assign group ID value to the "Group" with the conditional value setting illustrated in this screenshot.

Note that you have to sort the features beforehand if they are not ordered by group. e.g.

1. AttributeManager or AttributeCreator: Create a list attribute containing two elements - ID and OVERLAP_ID values. e.g. "_id{}".
2. ListSorter: Sort the order of the list elements by alphabetic ascending.
3. Sorter: Sort the features by _id{0} alphabetic ascending, _id{1} alphabetic ascending.

Additionally, the ListCombiner (FME Hub) might also be helpful. I designed this custom transformer for the purpose similar to your case.

The groups I've illustrated are simpler than those that exist in reality. It is not possible to sort the features into logical groupings and then assign a value, e.g. the following is also a valid scenario

A overlaps B Group 1

B overlaps A Group 1

B overlaps D Group 1

D overlaps B Group 1

C overlaps E Group 2

E overlaps C Group 2

D overlaps A Group 1