If you take off the elephant garlic flower, you will get a slightly bigger bulb, but I have found it has very little impact. They make no seeds or bulbils like other garlics. I've never seen seeds on topset onions, but each of the bulbils, no matter how many stages up, can make new onions. When there are larger bulbils, I may break them apart to replant, but for the smaller ones I'll just plant the whole clump.

My egyptian onions will set a cluster of topsets and then grow a second cluster atop that one. Sometimes there are flowers mixed in but they never seem to develop all the way. The second cluster of topsets is always smaller so I usually just snap them off early on. I haven't done a side by side comparison to confirm but I feel like snapping off that second, smaller cluster puts more energy towards the first and results in larger topsets.

I only grew elephant garlic for a few years and that was several years ago. I always removed the scape so can't comment on how it affects bulb size.

Rodney

I ended up leaving the scape on the elephant garlic and removing the top segment on the topset onions. That last was nice and mild oniony, a bit sweet with a tiny bit of a bite, and hopefully will . I put that with my garlic scapes off the Music and the Siberians. Compared to everything else in the garlic beds this year, the Music is far and away the biggest and most robust. Even many of the Japanese have scapes this year, and a lot of them also have stem bulbils. They are starting to look a bit ratty and shouldn't be too far off from harvest, say a couple of weeks.

A little late, I know...

"Second thing, my topset onions, set bulbils at the first joint but then
sent a second from that point that seems to be ending in flower buds. Do
these topsets ever set seed?"

Occasionally those flowers will set seed; but most often, the flowers are very few, and sterile. One of my top setting onions (a white bulbed variety) also has numerous flowers this year, and a nesting onion is flowering at the same time - so I will be watching the top set blossoms closely for fertile seed.

I pruned all the extra lengths off mine and they make good scallions. Raw they are initially a bit of sweet onion with a bit of a growing bite, but not hot enough to bother nearly anybody. No fiber for their entire length.

I expect that the top sets and the nesting onions are close enough to cross pollinate should there be fertile flowers on both. The top sets were originally interspecies hybrids IIRC. I have also heard that insects often spread allium pollen.

Bees have been working the onion blossoms, so I am hopeful of getting a little seed from the topsets. On another forum, there is a lot of interest in breeding with true seed from walking onions... I'll post any seed there. The flowers on the nesting onions will be cut off as soon as they finish blooming.

Both of the elephant garlics are blooming now. The biggest one is standing almost 5' tall. Both are also starting to have the lower leaves dry off as the blossoming progresses.