A pleasure to see these. Praise indeed to Minuteman and thanks to him for sharing.
With regard to officers, even regimental officers, we are still in the somewhat alien territory of being pre-uniform. Uniform = livery, livery = servant in contemporary minds, so it seems it was the best Marlborough could do sometimes to get his regimental officers to wear red along with their men. Matching the men's regimental facings was probably an ambition too far in many cases!
Thus, rank is largely apparent from the degree of decoration and subject to the individual's taste. Any impressively be-laced and be-wigged figure can be painted up as a senior, field or general officer in this period, and Minuteman furnishes us with a wonderful example of this.