Automate fill in boxes from one website to another website (both separatly owned)

Website A belongs to me - website B belongs to someone else (no coding or access available for website B) Website A has information fields like name address etc - website B has boxes where i can put information manually, but i want to automate it by clicking a button so A info gets into B fields without actually copy pasting every line. then i can submit manually in website B Eg. address in A and blank field for address in B - click a button that opens a link to B and address gets filled in B - now i just have to click submit in B