Nested API Button open form to add input, check box and redirect back to original form

I think that you are saying that this button has nothing to do with three of your four tables.   You just want a button to put the record you are sitting on into edit mode on form ID#11, and then you will require the user to input into a field and if they do and save,  then a checkbox will get checked and the user will be landed to display the record.

var text OpenInEditMode = URLRoot() & "db/" & dbid() &  "?a=er&rid=" & [Record ID#] // Suggested License ID
    & "&dfid=11"; // Not Applicable form ID

var text UpdateSuggestedLicense=URLRoot() & "db/" & dbid()
& "?act=API_EditRecord"
& "&rid=" & URLEncode([Record ID#])
& "&_fid_18=true" //Check Not Applicable to this Location
& "&apptoken=MY TOKEN";

var text DisplayOnRegularForm = URLRoot() & "db/" & Dbid() & "?a=dr&rid=" & [Record ID#]); 

$OpenInEditMode

& "&NextURL=" & URLEncode($UpdateSuggestedLicense)
& URLEncode("&rdr=" & URLEncode($DisplayOnRegularForm))