Wiktionary
back on to
vb. (context transitive English) (alternative spelling of back onto English)
Usage examples of "back on to".
The girl's face dropped back on to the concrete stoop with a wet smack that he could have lived without.
I intend to go up myself as soon as I've written a little in this book (keeping a journal under these circumstances may be dangerous, but God, it can be so soothing), then put it back on top of the kitchen cabinet where I keep it.