I can't tell which variety of blackeyed susans you have.
Some varieties of coneflowers get tall... like 6 foot plus!
You don't seem to have anything like that...
Most flowers will sprawl... when there's nothing holding them up.
Out in the natural world, they have plenty of companion plants holding them up.
If the companion plants disappeared in the wild, the flowers would sprawl there too.
When dealing with the 6 foot tall varieties, and a gardener obsessed with tidiness, a tomato cage works.
when dealing with plants that are two or three foot tall, you can either let them grow in the weeds like in nature... or try some of the plant supports that are widely available....
be aware that many of those things need to be set out early enough that the plants can grow into them.
Here's an example of what's out there:
As far as reproduction?
Try collecting some of the seed heads after the petals drop off... and see if scattering the seeds in new areas doesn't result in more plants.