I am no longer the liege on my heir, help me get it back please!

I am no longer the liege on my heir, help me get it back please!

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sommojames

Private
Sep 14, 2020
11
1
Here the situation. Long story:
1) as Matilada I married with a count from "Bosnia" (do not recall the real name of the faction, but it's where Bosnia is today), got an allied with that faction
2) my heir got some claims on a county in Bosnia
3) since I was conquering a lot of territory, I thought a good idea to grant a few titles to my living heir in northern Italy
4) from some weird succession law in Bosnia, and due to the fact that my heir was first claimant to a county there (even if he never controlled it) after some time my heir changed liege to a Duke in Bosnia
5) before I had the gather the necessary piety to ask the pope (my lover btw) the claim on the Bosnia duchy (just to have my son back), said Duke become part of Byzantine empire
6) now my son and heir has the f. Basileus as is liege

What can I do to get it back? I can declare war on the Basileus to get a claim on the duchy of Romagna (the counties of my son are all there), although I already have this title, so this is confusing

My question:
1) if a declare war to Byz and won, will my son get me back as his liege?
2) is there a diplomatic solution that does not involve war? (I do not mind war, actually I enjoy it, but I would rather not lose on time on something that should already be mine)

To complicate things I have 2 other male sons that are liege to the king of Sweden (my second husband was a prince there), but this is a problem for another time :)

Thanks in advance