We solved the problem by changing our thinking a little bit, P.S. the support at Zapier was great, and it all worked to redirect emails via Google.
However, the solution we have settled with is to send all the contact form data to one outlook email address, and then use the internal filters to scan the subject line of the email from Webflow (which has the specific contact form info) and forward them to the appropriate email address. So to summarise, the email client does the filtering as opposed to Webflow.
Cheers, hope that’s useful to anyone in the same boat.