Shared OneDrive for Charity Management Team

We are a small charity running a Village Hall in the UK. A few of the trustees form a Business Team that run the hall day to day. All of these have Office 365 personal or family subscriptions to use word outlook etc on their own laptops. The charity itself has Office 365 Business Basic Grant subscription. This give us Exchange email, OneDrive, Teams and SharePoint plus a few other bits. We currently store all our charity documentation on a free 15Gb OneDrive dating back to SkyDrive when first adopted. Each member of the team has their own charity Microsoft account and email e.g. email address removed for privacy reasons or email address removed for privacy reasons etc, etc.

I want to migrate this data onto an Office 365 Business OneDrive that is shared with this Business Team

Here's the rub. As most users have a personal subscription and data saved on their own OneDrive keeping the two separate is problematic. Because Microsoft credentials are so tightly integrated between the OS and Office if they try and sign in to the existing OneDrive it takes them to their own private OneDrive.

To work around this they have to use an Incognito browser session in order to log in.

I am aware you can create a shared OneDrive for teams as described https://support.microsoft.com/en-gb/office/create-a-new-shared-library-from-onedrive-for-work-or-school-345c8599-05d8-4bf8-9355-2b5cfabe04d0   which should allow them to access this OneDrive by using their own credentials as above (email address removed for privacy reasons etc) but if they log in to this shared OneDrive once, and on the prompt that comes up at log in select "Stay logged in", can they keep visiting the site without logging in again and will they then have to use an incognito browser session to access their own personal OneDrive?

Sorry this is so complicated but its been a nightmare trying to keep this working

Many thanks

John