Create a list view layout based on your contacts tables. Put a drop down menu in the header base on your carer table. Use a script tigger OnObjectModify to run a script that performs a find based on the down menu. Then all contacts with that carer will be listed.
I would put all contact info only in the contacts table and not put contact info for a Carer in a different table. A field in Contacts can identify which contacts are Carer contacts and you can use that field in relationship, finds, sorts and portal filters whenever you need to see just the contact info for Carers.