The Edge Relationship Tool can be used to establish geometric relationships between parent and child frames. The Tool is shown in the InDesign Tool panel as 
When the parent frame is moved or resized, the distance between the nominated edge remains the same.
Here the bottom of the frame at the top is linked to the top of the frame below:
With the top frame set to resize it vertically, after population the result is:
To create a relationship, click the frame edge of the parent frame, then click the edge of the child frame. EasyCatalog automatically maintains the distance between both edges when the parent is resized or moved.
To remove a relationship, click an existing parent edge and the corresponding child edge.
When a frame is middle of chain is deleted, the remaining elements are re-linked to maintain the chain. See the result below where the pink frame is deleted. Notice the distance between the blue and pink frames is maintained. Automating relinking only happens for frames with single parent->child relationships on the same edge.
