Q.Allium-bluebell
Until this year only bluebells have grown, now an Allium seems to be coming from same source. Is this possible and can I split them for next year? Malcolm Harris.

Certified GKH Gardening Expert
It is likely that a seed has fallen into the bed. Likely from a bird or rodent. Onions and Bluebell are too far removed from one another on the evolutionary scale to hybridize.
Luckily, onions reproduce by division and by seed, so you will have plenty of opportunity to divide them.
Here is an article for the care of flowering Alliums:
https://www.gardeningknowhow.com/ornamental/bulbs/allium/growing-alliums.htm