All of the examples that the current experts is testifying to can be easily explained by the fact that BB and JM had control of both CB's phone and laptop during this time, probably when CB was asleep upstairs because she had to get up early to get to work at 7 AM for her job as an ICU nurse.
I am not tech savvy but....
My devices are synced by Google.
My alternate devices are not actual lines, no SIM cards, but work on my wifi.
I can and have used multiple devices simultaneously, most notably to post on WS on one device while simultaneously livestreaming the corresponding trial on another.
My Google history is synced.
Who's to say CB wasn't doom scrolling on her cellphone while JM and/or BB were active on her laptop?
Recently a man was found guilty of murdering his wife, incriminating Google searches were located on his son's iPad. The murderer made those searches on his cellphone, deleted them, but they were preserved in the history on the synced iPad.
IMO this is why CB's personal history intersects usage that didn't come from her.
JM herself said CB left her bag and laptop by the door.
Which is where JM got it... and used it. At the very same time CB was using a different device to make mundane searches.
I am Encyclopedia Brown and I just solved the Case of the Lying Laptop.
JMO