Series drift is usually blamed on the model. Look at the record instead. The character was described from memory at every job, and memory edits as it goes — a hairstyle softens, a signature detail quietly drops, and by frame nine the series holds two similar women instead of one. The repair is clerical, not technical. Write the character down once, on a chair card, and keep the card in the chair pocket where every job can read it.
A working chair card holds five fixed lines, always in the same order. Age — a plain number, and here a mature one. Hair — colour, length and one habitual style. Build — two or three words, no more. Face — one or two details that endure every crop. Signature — the detail that survives a tight frame. Everything else belongs to the changing line below the card: outfit, room, hour, light, pose. Changing lines are meant to change. Card lines are not.
The routine at the desk is simple. Paste the card, word for word, at the head of every prompt. Generate at the standard model cost of 6 credits and keep the best third. Spend on repairs, swaps and upscales only after the cull, and judge every result against the card from the pocket — not against the previous frame, which may itself have drifted.
A chair card cannot hold a character who was never decided. Decide her on paper first. The card is not where the imagination happens; it is where the imagination is kept, frame after frame, in the same pocket.