Hi DorothySela,
Thanks for contacting us here again. I'll be glad to share more info so you're on the right path with achieving your QuickBooks goals.
Similarly to your bank feeds, QuickBooks allows you to add another Square account. However, the possibility of this is also in the integration app you're using. If you're syncing the transactions through the bank feeds, you can add another accounting using the steps provided in this article: Connect bank accounts to QuickBooks.
Let me know if this info helps. I'll be here in case you need additional assistance.