Price list update through form personalization

One of our customer requirement is, on specific condition the price list needs to be updated to desired pricelist, which is not part of secondary price list. For the same, we are trying to explore through form personalization. The form personalization is working, but on top of it the secondary price list is overriding. Any other way we can achieve this ?

Eg:

Sales order 123 having header price list 'A', secondary price list as 'C'.

Sales order line xyz is not in 'A' and need to derive as 'B' (xys is part of secondary price list 'C')

Form personalization is populating 'B', Secondary price list is updating it to 'C'.