• brother-inlaw,
• brother-in-law,
• vrothers-in-law,
• nrothers-in-law,
• hrothers-in-law,
• grothers-in-law,
• beothers-in-law,
• bdothers-in-law,
• bfothers-in-law,
• btothers-in-law,
• b5others-in-law,
• b4others-in-law,
• brithers-in-law,
• brkthers-in-law,
• brlthers-in-law,
• brpthers-in-law,
• br0thers-in-law,
• br9thers-in-law,
• brorhers-in-law,
• brofhers-in-law

The adjective form of "brothers-in-law" is "brother-in-lawly". However, this is an uncommon form, and it is more typical to use the noun as an attributive adjective without modification. For example, "They are my brothers-in-law".