Add user to Sendgrid list after adding to Perch forms

I am currently using Perch forms to keep track of two forms on my site. One for subscribe, and one for Contact. I am now trying too connect that form submission to a SendGrid account where the client does all the marketing emails through. At the moment, I can either submit to Perch, or too SendGrid, but not both. The reason I would like to submit too both, is that we are using Perch with a few apps for this project, and it would be perfect for the client to have a list of everything all together.

I originally started with the the form submitting to Perch, and thought that I could chain it to the form submit with an Ajax call. I then realised that the forms submit with the app attribute in perch:form, and action over writes that when it is called. The end result was getting one or the other.

I then tried to isolate where the information is added to Perch and include the .php script there, which I didn't have much luck in, I don't think I want to mess with the app too much, yet. I also tried to wrap the script like an app, then call it as the second argument in the app attribute, but I had runtime errors.

I haven't really dived into any of these options just yet, as I would like too know the best way to go about it, without going too crazy.

Thank you.