Yes, multiple companies can be simultaneously linked to one and the same user, the user can switch between the companies he was granted access to with the same login.
Each user can access multiple companies with the same login credentials. Access is granted by the administrator of the company. Here there are 2 possibilities: the administrator adds the company himself, or the user is invited by the other company. On the platform, each company (unique VAT number) can only appear once. If the company is already active on the platform, it can grant the administrator access to its company.
If a company grants access to someone who does not belong to the company, it will also include which locations the remote employee can see.
If your company has multiple branches or entities but the same VAT number each time, the company will be created once and the classification will be done based on "business unit". Business unit are also a component to grant access to users.
If the company does not exist on the platform and employees use the construbadge or metalbadge, then this company is automatically created on the platform. The company linked to the construbadge is not accessible for consultations, within the platform this is called a "private company", which is only used for information to checkinatwork and interrogations by the company where the badge has been used.