A to Bm7
How to transition from an A chord to a Bm7 chord.
The A → Bm7 transition is the same V → vi7 move in the key of D.
Chord shapes
Play the A chord in an A shape, and transition to a Bm7 chord. Keep your second finger in place, slide your third finger up a fret, and move your first finger from the D string to the A string.
AFull
Bm7Basically D/B
Anchor fingers: finger 2 on G string (fret 2)