Whether or not families get together over the years when they live apart varies a lot. Cost and the size of families (as well as how “close” everyone feels) may affect frequency of travel even in Southern families. After they moved to California, the Turpins were far away and could use that as an excuse.
What is more interesting is that they apparently refused to let Louise’s mother visit.
The other side of the family (David’s) had later contact.
I believe DTs parents last saw the kids five years ago or so.
And Randy Turpin and his family visited and they all went to Disneyland together in 2011 (going from memory here).
A homeschool “highschool graduation” does not have anything to do with the school district unless the family is doing their homeschooling through a school that has been accredited by the state and the kid gets the diploma from that school.
In most states that allow homeschooling, there is NO mandatory testing or proof that the kids are actually making grade/age appropriate progress.
In California, all the parents had to do was report “attendance” and the grades the kids the kids were “attending.”
Here is a link to information about homeschooling by state.
https://www.responsiblehomeschooling.org/policy-issues/current-policy/