When creating multiple readers, it's not really a neat and nice process to assign the same search envelope to all of them. There are three main ways I suppose:
1) Manually input it on all of them. That's 4x input per feature reader. Copy-pasting helps obviously, but still a lot of manual input.
2) Create four user parameters with values, then link the parameters to each reader. Less writing, more clicking - still a lot of input.
3) Have a creator that creates the box and then use multiple feature readers to check for intersection. Slightly nicer, but doesn't create as good a workspace and doesn't support clipping.
Neither of the above ways are really simple or satisfactory for what seems to be a straightforward approach.
Instead, I suggest some kind of "link to other reader" or "copy from other reader"-solution for the bounding boxes. This way, you'd set it for one of the readers and then point the others to use the same values and settings as the first one.
(Slightly inspired by https://knowledge.safe.com/idea/34353/use-a-map-driven-dialog-when-asking-users-for-boun.html which I think is a tremendous idea and a much better solution for bounding box inputs. However, it'd still be a problem for multiple readers, unless they can share search envelopes)
