I think the important thing is that you are delving back into waters you have been out of for a long time. To ask for these boundaries to ease back into sharing the person your love is completely understandable IMO. I would find it hard to believe that your partner would take issue in looking after the person she has loved for so long by being very accomodating at the inception of a new relationship.
To do otherwise perpetuates the selfish aspect of poly in my opinion.
Playing the Game of Life with Monopoly rules.
Monogamy might just be in my genes
Poly Events All Over