Yes. The girls’ situation is very uneasy, they have one remaining parent, and each other. I feel very sorry for them.
To compare with the two recent Coloradan annihilators, what they do immediately after murders tells a lot about motives. CW sends photo of flowers to NK (romance); PF’ s mom and sister move for guardianship of his daughter (desire for sole ownership of the child mixed with certain paranoia).
The first thing Barry did was move for guardianship of SM in Indiana and also requested to sell jointly owned real estate in Indiana on her behalf.
My intuition tells me the main motive of BM will be greed, probably, mixed with unwillingness to go through costly, lengthy, divorce.
There are probably lots of other people somehow involved on the sides, and high drama, but IMO, it is less of control and more of utilitarian approach to life and people, well, peaking around his “critical age”, too,