ThePiggy
Fishaholic
Sounds good!
UPDATE:
I bought a fry net tonight to put Dolly aka Miss Piggy in during feeding time, and I am happy to report that all my babies are eating! Yay! It was funny/cute 'cause the little ones were wondering what the heck the net was and why Dolly was in it! Also some of the pellets got stuck to the filter, but Patsy figured out how to pluck 'em off LOL too cute and smart! I am still sad/upset about the ripped/torn/split fins, but I know that in time they will grow back. I am just glad that all of them seem to be getting along much better for the most part! Hopefully only things get better and better!
For future reference, I'd just like to mention that 'seeded' filter media needs to go right into the filter, as I don't recall noticing any earlier specification in this thread.
That way the ammonia/nitrites in the water drawn into the filter circulate endlessly over/through the bacteria in the media, which will gradually increase their population and, hence, detoxifying ability according to the food supply, meaning the number and size of fish and any other inhabitants such as invertebrates in the tank which may be producing 'nutrients'.
If the media doesn't fit in the new filter, and you're only using the one tank/filter, the next best thing would be to run both filters for a while, assuming the old one was used within hours on a tank containing fish.
I don't know how your tank is constructed, but on the old-fashioned, basic, canopy type, two HOBs can usually fit in behind, if you have the type with the detachable piece in that area, or otherwise if the light fixture can be separated from the rest to sit on top of the tank, as on my cheapo ones, with Saran Wrap or some such thing forming an inverted trampoline in case of attempted jumpers.
Then, once the new filter and tank are seeded, the old filter can be removed and the tank assembled normally.
However, expensive name brand tanks with built-in everything have become popular, and I've no idea on those.
Melafix, at a half to 3/4 dose, depending, (and don't buy the expensive Betafix which is essentially watered-down Melafix at a higher cost for less) can help torn fins heal well - and a healthy betta heals quickly.
Bettas have to because they (especially males) do tend to have territorial issues and even the nicest betta girls will likely have spats here and there for probably quite some time, unless the pecking order is accepted on a permanent basis, something not likely to happen.
Rather like horses in the pasture, if you've spent time with any.
As advised by others above, lots of 'privacy' will help enormously, and that previously suggested piece of driftwood, thoroughly boiled if at all possible to reduce excess leached tannins and to kill bacteria, mould, fungi or any other nasties which may have arrived with it, would be ideal for forming part of that.
Not only would this provide shelter but help to produce a softer, more acidic water your bettas would appreciate.
And I don't want to make you nervous, but I'd suggest keeping half an eye on the girl with the big tummy.
She's probably fine, and it'll undoubtedly go down shortly if it hasn't already, but if there's any sign of white, stringy poop, you may need to do a little worming or treatment for internal infection - although good luck on sorting out which, if no excreted worms are visible, as they rarely are.
Behaviour is also key: extreme nervousness and/or aggressiveness can be caused by many things, but it's also one of the symptoms of nematode/worm infestation, so if any such signs are present, good observation skills help in attempting to identify any potential problem.
But the odds are good you'll have no serious problems as long as stress levels aren't high, and with plenty of hiding places and the dedicated care you're giving them, I'm sure your lovely girls will live long and healthy lives, making your heart sing.
Probably country tunes, I'm guessing.