Sounds ok to me too hun. Just think about it like this - what goes in must come out so if they are eating so frequently then they will probably have frequent bowel movements.
My cat eats several times a day and has always done so. I just replace his dry bickies when the bowl is empty ro top it up at dinner time. They won't just eat and eat and providing they are lively and happy then I would assume there is nothing to worry about.

Nae x