Also I found this interesting which would also not align with what Grandma is saying:
"Houston police searched the
Gateway at Ellington apartment complex Monday.
Texas Equusearch planned to conduct a physical search Tuesday
, but it did not happen, saying the stories given to police don’t add up, which makes it difficult for them to know where to start. Police said the last time they can independently verify his location is on April 30 when he was at school. Samuel’s paternal grandmother, Tonya Olson, said he was with her the following weekend. Olson said she heard him on the phone a little over a week ago."
It also states in this article it seems that Tonya Olson is Samuel's fathers Mother so there is connection there with the Dad, the GF, and Grandmother. Also if Grandmother is lying this makes sense as to why they have Sam's mom IDing him.
SOURCE: Police: Body believed to be of Samuel Olson found in Jasper motel | khou.com