How to link one contact to multiple projects？
Sometimes, one contact may be involved in multiple projects. In this case, you could use CRM user alias. A CRM user alias is an email alias of yours that ends with '+crm'. E.g. if you email address is '[email protected]', then you could use 'email@example.com', 'firstname.lastname@example.org', etc.. as CRM user alias.
In general a CRM user alias has a higher precedence when deriving the project from contact.