coincidently, uncoincidentally, noncoincidently, coïncidentally, noncoincidentally, strangely, incidentally, fortuitously, as it happens, synchronistically, more...

accidentally, fortuitously, serendipitously, unexpectedly, incidentally, more...

happens to be,   happened to be,   just so happens,   so happened,   just so happen,   by fate,   just happened to,   it so happens,   it just so happens,   not conincidentally