It sounds like you need to be looking at the API for these to programatically handle such events without them being opened.
have to ask though, what is the reasoning behind having a seperate form that you want to update silently but still then want to invoke routing ? if an action on your ‘parent’ form is to trigger an action to involve someone else, then why not run it all from this form? I’m sure there may be valid reasons for you wanting to do this, but it could also be that there is a different way to approach the overall process and there may be a lot simpler way to achieve what you are after here. perhaps contact us via the support ticket and we can open a conversation to try to help you find a more effective way of acheiving your aims
as to the options in the form field, these are ‘variables’ and as such have no bearing on how you need to define the form field to need to define. Technically they could be removed from this area but as they are ‘shared’ with other application functions it helps the overall product where a seperate control just for Set/Get Field instance isn’t then needed