Stripes will not grieve in the sense people do. Stripes will miss the comfort of Blackie as there is safety in numbers.
Same size Thamnophis would be fine only after a quarantine period of at least 90 days.(in my opinion)
The necropsy is your call. If it helps answer some questions and makes you feel better then get it done if you can afford it.
Post up some under tail photos of Stripes and we'll sex her/him. I'll also link you to a page to show you the type of photos to post. It's also a great page to learn what the different sexes look like.
Best to house same sex unless you want little scrubs popping up.
Miscarriage is more of a mammalian term. Passing slugs or jellies would be appropriate for a Thamnophis. Seen many slugs and jellies in my time. Most of the time the snakes do fine afterwords.
You are not using the forum as a crutch so don't think that. This Thamnophis family is here to help you.
Keep your head up. Most if not all of us have lost snakes and some have been a direct result of what we did or didn't do.
http://www.thamnophis.com/forum/bree...xing-pics.html