Return to Answer

 [FEN "b3r3/1R1p1p1q/1p1P1P1b/1Pk1BR2/1rN1K1Nq/p7/P1P1B1P1/1qn1q1nq w - - 0 1"]

Here is an (ugly) suggestion wth 29 units.

White is stalemated with 8 pins; removing any Black unit would break the stalemate.

White has promoted one of her three missing pawns (to knight) and black has promoted all of her five missing pawns (two into rooks, two into light-squared bishops, and one into a knight).

The four captures (white queen, 2 white pawns and 1 black pawn) ensure that this position is reachable. I am pretty sure we could add at least one of the missing pawns but that would require some retrograde analysis to prove the legality of the position that is beyond both my motivation and my available time. For instance, adding a white pawn on b2 doesn't work because it won't be possible anymore to promote all black pawns.

 [FEN "b3r3/1R1p1p1q/1p1P1P1b/1Pk1BR2/1rN1K1Nq/p7/P1P1B1P1/1qn1q1nq w - - 0 1"]

Here is an (ugly) suggestion wth 29 units.

White is stalemated with 8 pins; removing any Black unit would break the stalemate. Black has promoted all of their four missing pawns (all into queens).

The three captures (white queen and 2 white pawns) ensure that this position is reachable. The three missing White pieces ensure that the position is legal and that Black could have promoted all four of their missing pawns.

The Black g-pawn captured the White h-pawn to produce doubled pawns that both promoted. The Black c-pawn captured the White queen to bypass the White pawn structure and promote. Finally, the White e-pawn was captured and then the Black e-pawn marched down and promoted.

This is optimal because 4 pawns must be promoted to create 8 pins, with requires a minimum of 3 units, thus leaving 29 left for the final position.

[FEN "qn1r2b1/1N1BpRn1/1p3bP1/rN1K2Br/P3P2p/nR1N1b1P/b2r4/k7 w - - 0 1"]

Here is an (ugly) suggestion wth 28 units.

White is stalemated with 8 pins; removing any Black unit would break the stalemate.

White has promoted one of her three missing pawns (to knight) and black has promoted all of her five missing pawns (two into rooks, two into light-squared bishops, and one into a knight).

The four captures (white queen, 2 white pawns and 1 black pawn) ensure that this position is reachable. I am pretty sure we could add at least one of the missing pawns but that would require some retrograde analysis to prove the legality of the position that is beyond both my motivation and my available time. For instance, adding a white pawn on b2 doesn't work because it won't be possible anymore to promote all black pawns.

 [FEN "b3r3/1R1p1p1q/1p1P1P1b/1Pk1BR2/1rN1K1Nq/p7/P1P1B1P1/1qn1q1nq w - - 0 1"]

Here is an (ugly) suggestion wth 29 units.

White is stalemated with 8 pins; removing any Black unit would break the stalemate.

White has promoted one of her three missing pawns (to knight) and black has promoted all of her five missing pawns (two into rooks, two into light-squared bishops, and one into a knight).

The four captures (white queen, 2 white pawns and 1 black pawn) ensure that this position is reachable. I am pretty sure we could add at least one of the missing pawns but that would require some retrograde analysis to prove the legality of the position that is beyond both my motivation and my available time. For instance, adding a white pawn on b2 doesn't work because it won't be possible anymore to promote all black pawns.

[FEN "qn1r2b1/1N1BpRn1/1p3bP1/rN1K2Br/P3P2p/nR1N1b1P/b2r4/k7 w - - 0 1"]

Here is an (ugly) suggestion wth 28 units.

White is stalemated with 8 pins; removing any Black unit would break the stalemate.

White has promoted one of her three missing pawns (to knight) and black has promoted all of her five missing pawns (two into rooks, two into light-squared bishops, and one into a knight).

The three captures (wQ, 2 white pawns and 1 black pawn) ensure that this position is reachable. I am pretty sure we could add at least one of the missing pawns but that would require some retrograde analysis to prove the legality of the position that is beyond both my motivation and my available time. For instance, adding a wP on b2 doesn't work because it won't be possible anymore to promote all bPs.

[FEN "qn1r2b1/1N1BpRn1/1p3bP1/rN1K2Br/P3P2p/nR1N1b1P/b2r4/k7 w - - 0 1"]

Here is an (ugly) suggestion wth 28 units.

White is stalemated with 8 pins; removing any Black unit would break the stalemate.

White has promoted one of her three missing pawns (to knight) and black has promoted all of her five missing pawns (two into rooks, two into light-squared bishops, and one into a knight).

The four captures (white queen, 2 white pawns and 1 black pawn) ensure that this position is reachable. I am pretty sure we could add at least one of the missing pawns but that would require some retrograde analysis to prove the legality of the position that is beyond both my motivation and my available time. For instance, adding a white pawn on b2 doesn't work because it won't be possible anymore to promote all black pawns.