If a petty kingdom is vassal and assimilates into a high kingdom then the former petty king and all of his dukes become independent. The following chunk attached to the beginning of the immediate block for each petty( substituting the particular petty for [PETTY]) corrects this:
any_vassal ={
if = {
limit={
has_landed_title = [PETTY]
not = {num_of_king_titles = 2}
}
any_vassal ={
if ={
limit={ or = {
tier = duke
and= {
prev = {not = {num_of_duke_titles = 1}}
tier = count
}
}}
set_defacto_liege = prevprev
}
}
[PETTY] = { destroy_landed_title = yes }
set_defacto_liege = prev
}
}
any_vassal ={
if = {
limit={
has_landed_title = [PETTY]
not = {num_of_king_titles = 2}
}
any_vassal ={
if ={
limit={ or = {
tier = duke
and= {
prev = {not = {num_of_duke_titles = 1}}
tier = count
}
}}
set_defacto_liege = prevprev
}
}
[PETTY] = { destroy_landed_title = yes }
set_defacto_liege = prev
}
}