I agree with Ben and King, there is big risk but it can be done with a little luck.
If you're feeding a good ammount and keep your bichirs thick but not fat, you'll be okay.
When I feed my bichirs get lumps in their belly but almost look thin by next day (weather is warming up in socal so they have to breach for air more often).
My largest bichirs are 11" laps, and my smallest is a 4" ornate, crazy I know, but I had to mix them in an emergency. The ornate goes at the food with all the big boys with no second thoughts and all is okay.
Now if my 10" plus bichirs were aggressive, this would be impossible, but mine seem to be fairly placid and more interested in massivore and tilapia than their tiny roommates.