"So for example I fill out appliance 1 details and tests I've done on that appliance and if the appliance fails it says have you attached a "warning notice" I would put yes and then when submitting to the next page of the form it would either add a subform or link me to another separate form that would be the warning notice now this warning notice would also need it's own unique ID like the original form and I'd also like this warning notice to be sent to the same record in the CRM rather than creating a new record entirely. I know forms has redirects and subforms etc and I'm pretty sure I'm close to achieving what I want but I'm just not seeing it.

Can anyone shed any light on how I could accomplish this

The other way would be to show/hide a page from the PDF would this be possible from the response. So if I put no warning notice the PDF would just show the first page of I selected yes add warning notice then the PDF would show pages 1 and 2 "2 being the warning notice" now I have up to 3 appliances per form and each would need to have this as an option as each may have a warning notice. What I don't want is to get to the end of the form and have 1 certificate and then 3 separate warning notices under 4 separate records in my CRM as that will get confusing to which notice is from which certificate etc. 

Hope this makes sense and really hope someone has a way of achieving this outcome