No, that is not how it works in RoE. Just ask Assan when he transfered his bloodline to Rashid.
I want a slight boost, yes, but nothing like a old and resepcted regent transfering his buffer up BS to his Heir. The Heir gets a slight edge there at the start, but transfers fo regency are traumatic affaris for all domains, not just one regnet in and one out.
So this item is not even debateable (or rather, feel free to debate, but there will be no rule change).