coadjutress

She appointed Agnese de Sellis her coadjutress, and begged her to share her room, and watch over her conduct, entreating her at the same time to warn her of every fault she might commit.

The Life of St. Frances of Rome, and Others Georgiana Fullerton 1848

Thus then, as before stated, a hollow peace was patched up between the unequal rivals; and Madame de Verneuil at length found herself in possession of a folding-seat in the Queen's reception room; while her coadjutress triumphantly took her place among the noblest ladies of the land; but scarcely had this result been accomplished, when Henry, profiting by so unhoped-for an opportunity of gratifying the vanity of the favourite, assigned to her a suite of apartments in the Louvre immediately above those of the Queen, and little, if at all, inferior to them in magnificence.

The Life of Marie de Medicis Pardoe, Julia 1890

Thus then, as before stated, a hollow peace was patched up between the unequal rivals; and Madame de Verneuil at length found herself in possession of a folding-seat in the Queen's reception room; while her coadjutress triumphantly took her place among the noblest ladies of the land; but scarcely had this result been accomplished, when Henry, profiting by so unhoped-for an opportunity of gratifying the vanity of the favourite, assigned to her a suite of apartments in the Louvre immediately above those of the Queen, and little, if at all, inferior to them in magnificence.

The Life of Marie de Medicis — Volume 1 Julia Pardoe 1833