4 letters:
bala, bali, bela, beli, belo, bely, bila, bily, bola

5 letters:
baali, baila, baily, balaa, balah, balai, balao, balay, baler, baley, balla, balli, ballo, bally, baloo, balor, balow, bayly, belah, belau, belay, belee, belew, belie, bella, belli, bello, belly, below, beula, bhili, biela, biler, bili-, billa, billi, billo, billu, billy, bilow, birla, bi lo, bolar, boler, boley, bolla, bolli, bollo, bolly, bolye, booly, boyla, bulau, bulla, bulli, bully, burla, burly, bvrla, bylaw, byler, by la

6 letters:
baalah, baelor, bahler, bailar, bailee, bailer, bailey, bailie, bailli, bailly, bailor, baligh, baller, ballet, ballew, ballor, ballou, ballow, balogh, bawler, bawley, baylee, bayley, baylie, baylor, bealer, beeler, behler, beiler, bellah, bellar, bellay, beller, bellew, belley, bellow, berley, be low, bhalla, bhilai, bieler, billao, billar, biller, billie, billow, billye, bill o, birlaw, birler, birley, bi lao, bohler, boiler, boller, boulay, bouler, bouley, boulot, bowler, bowley, buelow, buhler, bullae, buller, burlar, burlew, burley, by-law, byelaw, by law, by lay, by lee, by low

7 letters:
bailler, baillie, ballare, ballowe, beehler, belleau, biehler, boehler, boileau, boulais, bouleau, bulleux, bye-law, bye law

8 letters:
bailleur, belleair, bill lee, bouillir, burleigh

9 letters:
boyle law