Official comment
You can have your employees fill out a similar form and, as long as they use the person's email address, the form will create a new or update an existing Contact with that email address.
To do this you must use the legacy (older style) Smart Form in Contacts > Forms, and not an ONTRAform.

You can embed this form on an ONTRApage using the Custom HTML block, or on a legacy Landing Page, and then host it on one of ONTRAPORT's provided domains. In the page's settings, make the page it's own Thank You page and with every submission the page will refresh. Like the other opt-in form, you can have the form subscribe the new contact to the same sequences, tag them, etc.
IF you want to use an ONTRApage and the built in forms on them you have to follow the instructions found here: https://support.ontraport.com/hc/en-us/community/posts/245423647-My-ONTRApage-form-I-m-using-to-update-contacts-keeps-overwriting-them- ONTRAforms and native forms in ONTRApages submit based on cookie data and need that modification in order to flush the cookie data before submitting again. That's a bit complicated, so my recommendation is to simply create a legacy Smart Form as described above.