You really need to separate them. Regardless of sex they are too young to be housed together and clearly there is a problem is one is not eating.
When I say tubbing I mean in something TINY and dark.
First off you need to get her her own enclosure - let her settle for a week, then try again.
5.2.0 Corn snake 3.1.0 Milks 0.2.0 Kings 1.0.0 Northern Pine 2.0.0 House Snake 1.1.0 BREDLI!
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