Because what I say below may be wrong, I’ll preface this response by recommending that you check with each of the stock websites to see what is or isn’t allowed.
That said:
To the best of my knowledge, license rights to stock media cannot be shared in the sense of two parties using a single stock license in a separate and independent manner.
So if that’s what you mean by “sharing”, then since you purchased the stock, unless you were able to specify otherwise at time of purchase, you are the sole license holder. Neither the owners/copyright holders of the stock nor the stock websites are likely to give legal authority to a license holder to grant license holding rights to another party.
To my knowledge, if both of you want to “share” the purchased stock media in a way that’s completely separate and independent of each other, then it would be necessary to make a second purchase of all stock to be “shared”. The license holder for the second purchase would be whoever isn’t already the license holder from the first purchase.
If you mean “share” in the sense of you being able to use the stock for your client’s benefit (that is, only for this one client’s projects), then the solution could be to contact the various websites and ask them to change the license holder to be your client instead of you.
But again, I would double-check with the stock websites to see what is and isn’t allowed concerning this matter.