I’ve considered that Lori and Alex took the kids to Yellowstone with a plan to kill one or both of them there, then had to abort the plan for some reason. If their original plan was to kill them there, I’m comfortable assuming that they planned to do so because they thought it was a good place to leave their bodies. Why else?
If that were the case, and they chose to abort that plan, they still chose to murder Tylee that night, IMO, after they returned. In that case, I would agree with you about why they buried Tylee on Chad’s property. Later, they would have buried JJ there, as well, to minimize the separate locations that they had to monitor.
This could make sense, as Tylee’s burial spot is in a poorly planned location on the property; it’s close to the residence and in a spot that family members could try to dig (the pet cemetery). However, JJ’s location seems like more forethought went into it.
I don’t know that Chad and Lori actually planned to keep the children on the property indefinitely, but they would need to keep them there until the attention died down. After that, if they relocated or sold the property, they could also attempt to relocate the children. IMO, Tylee would be nearly impossible to fully remove from the property but, as I’ve said before, I don’t think Chad and Lori are smart. so that probably wouldn’t stop them from trying—if that was what suited their needs at the particular moment.
That said, in the short term, Chad would have a much greater need to deal with Tylee’s burial spot than JJ’s—after all, she was buried in the pet cemetery. How long would it be before someone in the family attempted to put another pet there? A modular home would have allowed him to quickly cover her, but also potentially allow him access later.
IMO, In his mind, JJ could be dealt with later because, in the short term again, it was probably less likely that someone within his household would go digging by the pond.
All JMO. My apologies if some of the language comes across as callous, regarding “dealing with” the kids. I meant to reflect how Chad and Lori so callously (monstrously!} treated the children.
ETA: Punctuation.