Newsletter sign up field in forms

Site URL: https://www.lionatpennard.co.uk/get-in-touch

I have various forms on my site, and separately have newsletter sign up blocks. However, is there a way of adding a newsletter sign up field on a form...it seems like an obvious feature that doesn't appear to be available. Surely anyone sending a contact form, for instance, should have the option whether or not to be added to a email database? Thanks

have the same issue.  Currently sending name and email address to google suite with a bunch of form fields and then back-porting the name and email list into my subscriber list in Squarespace.  Seems like a waste of time.  

I would like to see the name and email be sent to google suite AND to the Squarespace subscribe list that the form is for.  I'm trying to build an email campaign system but if I'm constantly having to check for new subscribers in google suite and do the back-porting, it takes the automation out of the equation.

Any help on this?