I agree, if you are going to get more fish give the rummies and neons some more friends. I have 6 rummy nose in a 29 gallon and I think that is really a minimum number for them. Same for neons.
BTW, neons get bigger than 1 inch, probably about 1 1/2 inch. I have heard that the cories don't really have to count as much as other fish toward bioload because they are such effective cleaners, so you could probably get away with 1 or 2 more platies, just make sure you have something to do with all the fry
LOL!
And Soylent Grundy is right, don't add them all at the same time, maybe 3 tetras then wait a week or 2, then 3 more, then a couple platies or something. Make sure you have adequate filtration.
The 1 inch of fish per gallon rule is kinda suspect
IMO, it works ok for smaller fish like yours but could you imagine keeping a 10 inch Oscar in a 10 gallon tank?
BTW Lance, your 10 gallon is waaaaaay overstocked, what kind of filter do you have?