Lady Inayah, a noble by birth, naturally possessed far greater resources than a lowly pleasure slave like the Queen Mother. For example, she received a handsome monthly stipend, as well as maids and various servants, high quality food and drinks, and new clothes every year from her family, allowing her to live a very comfortable and luxurious life in the palace.
And all this was on top of what the palace usually provided from its own treasuries. Thus even though Lady Inayah was perhaps not the richest of all the imperial concubines, she was certainly up there.
This wealth, she was also gracious enough to share this with her red haired friend, giving her as much as needed whenever she asked- in fact it was courtesy of Lady Inayah that the Queen Mother did not suffer in the palace as much as she should have from the machinations of the other concubines.
