I decided to err on the side of caution and bring Tudor and Bronwyn inside, tonight
Their mom is ignoring them and hasn't even nursed them, all day. I made them some slurry and it was obvious they were VERY hungry. She is taking care of the other two and I have no idea why she's ignoring these babies. I even put their bed right by the shelter, to no avail.
It's going down to the low 50's tonight and both kittens have been leaving the bed I made for them and wandering around the garden and yard, meowing loudly. That just seems like a huge risk. I put so much effort into saving Tudor, today, I don't want to risk something happening to him. They can spend the night in the playpen with a nice warm bed. I'll return to my usual kitten feeding schedule, which means less sleep but more peace of mind.
The weather will be really nice, tomorrow, so I'll take them back outside. If their mom continues to exclude them, I'll just have to take over. They won't be joining the inside kidcats. I'll just have to figure something out.
= new reply since forum marked as read
to you and your kittens. 
Can be as good as sleep sometimes. 
Kick in to the DU tip jar?
This week we're running a special pop-up mini fund drive. From Monday through Friday we're going ad-free for all registered members, and we're asking you to kick in to the DU tip jar to support the site and keep us financially healthy.
As a bonus, making a contribution will allow you to leave kudos for another DU member, and at the end of the week we'll recognize the DUers who you think make this community great.