Importe feature from part B to part A

Hello, I do have the following configuration:
Part A : STEP file with unrecognized feature on top of the three.
Part B : SW model
I would like to replace the Imported3 feature of part A by the Dome feature of part B, or the reverse, get all recognized feature of part A into the part B.
What will you do to split away the unrecognized feature of part A "imported3" to be able to insert all other feature into part B?
4 Answers

I tried to use Split feature, but I don't have any more the three feature inside the split part!
The top part is gone, but it is useless as I lost other feature attached to this body.

New try:
Save the split as STEP file
Open the STEP file and used Automatic feature recognition
I got he feature back, but I still have top of the tree with unrecognized feature!
Sadly, I'm back to the initial point.

Finally, this is what I did:
- Create a new sketch by extracting the profil from the part (using intersection curve).
- revolve this new sketch.
But, I'm wondering if this method is safe to reproduced the existing STEP part, because while adding the extra body part (the one that can't be done using revolve), I notice that the curve don't match perfectly!
I don't create any sketches by hand, I just reused the one inside the STEP part.
But I use different feature, where the STEP part used 10 feature, I used only 2! Is my method the culprit?