Merging SHP located in different directories

I have one shapefile with polygons representing a cartographic sheets at some scale. Each polygon has an unique identifier (IDn).

I have used SpatialRelator transformer (see attached image) to look for neighbor sheets for each of them, and ListConcatenator to save for each polygon the list of neighbor polygons identifiers.

The attached example shows that selected polygon (ID0) has 3 neighbor polygons (ID1,ID2,ID3). The IDn is the identifier included in the shapefile name located in some directory following this pattern: .\\IDn\\*IDn*.shp

I have to merge the 4 shp corresponding to ID0, ID1, ID2, ID3 to output only one shapefile.

I have used Directory and File Pathnames READER in other context but here I don't know how to look for these files. Maybe using WorkspaceRunner or PythonCaller? Please, could you give some advice?

Thank you in advance!