I have a custom module called SMS, which has a lookup to the contact module. From the contact module I have the related list set up so that I can add new SMS (links to SMS custom module).

When i click new SMS i want to prefill the Mobile field in the SMS module with the Mobile number from the contact field without having to save the form first and run a (create, edit, update) workflow. is there a way to store mobile number (variable) and have it land in the mobile field in the custom module.

I have got the scripts to update the record after I save the record, but I dont want to have to save and then update again, as I have a webhook that sends an sms on save.