They are sure that one of these catholic schools is not part of the Consortium of Grammar Schools and so they had thought that if she had failed the 11+, she would have entered this school anyway. (hope this is clear).
Are you absolutely sure that these catholic schools were on their CAF? There is no "default" of being allocated into a school anyway just because she is at a catholic feeder school.
Presuming they were on the CAF - I think you need to find out why she was not eligible for a place at the catholic school. What are their criteria ? Sometimes it is specific attendance, sometimes it is just baptism .They will have a numbered list of categories and should be able to tell you how far they got down
eg "We allocated all in categories, 1-3 and had to use the oversubscription criteria for category 4".
Might help to say which schools they were then we can look these up