I recall when Isabel missing was on the news, and her father was on tv telling Isabel how they loved her and missed her.
The way he said it was so awkward, so uncomfortable, ever since I have felt Sergio is different than other people. He is so overly emotional in a way that I havent seen before, for example also when his wife talked and he looked at her while feeling her every emotion, so very intense so uncommon.
But Sergio is a theatrical men, he is a singer and actor, he has to put all his emotions into his work, and I think it is part of his IRL aswell, he cannot help being the way he is.
I do not think he harmed Isabel, same for Becca, she never ever would harm her child or punish her while doing her hair or over a remote or not wanting to sleep, I cannot see that happening.
Sergio may be a strange bird, but I think his love for his wife and children is inmense.
That leaves something occuring due to not watching out, something in the house, something between her and her brothers or a third party, anything is possible. I do not think her parents are suspects nor that they will be arrested.
I also do not think there will be answers, and I think the find was a happenstance even if that is being denied.