I don't like to use direct messaging as it limits who can see the information.
By posting things, many others can make use of the discussions that arise thereby maybe negating the need for them to get the same information in a separate thread of their own.
I have learned a lot just reading other hobbyist's postings over the years, here and on seahorse.org.
Having been involved with seahorses now for 13 years, but having studied their needs for a couple of years prior to that after being into reefing in a BIG way, I feel confident in telling you that the odds are that you don't REALLY know what you are getting into it. While there is the possibility, it is slim.
I've been a member of seahorse.org now since April 02 and that site was an offspring of another one no longer going now, but between those two sites, and this one, I've seen enough postings to know that most people only THINK they know what they are getting into.
It started with me after a couple of years of researching coupled with my vast reefing experiences I figured I should have no big problems with seahorses.
It certainly wasn't long before I realized I was wrong, and over time just how wrong I was. Unfortunately, I survived but not all my seahorses did.
Now, as for mixing the seahorses, it is probably wise to go through the deworming protocol before doing any mixing, to lessen the problems you may have when you do actually mix some. It is a 3 drug 9 week program that tries to minimize the pathogens that may be transferred from the one you have to the ones you will get.
You don't even know if it was true captive bred, or tank raised or net pen raised which increases the odds of failure upon mixing.
Pretty well ALL seahorses bought these days in North America are trained to eat frozen foods before they are sold. That goes even for the tank raised and net pen raised ones also.
True captive bred ones would be those raised in waters that have been properly treated and filtered for pathogens, or have been raised in commercial salt water like the ones I raise using I.O..
The ones that need to be trained to eat frozen are wild caught specimens in which many can be trained but sometimes it just won't work and they need live food exclusively. Fortunately there are very few of these around in the last few years in North America other than those caught by the keepers themselves who gather from along the coast.
You say your experience about seahorses is well known, but by whom? There is no indication of such extensive knowledge in any of your postings on this site so how would I know?
You don't sound like you are an ***hole, but I do feel that you sound like you are overconfident and quite young.
I still recommend going slower and if you manage to keep a pair of erectus alive for 8-12 months then you will be much more likely to succeed with larger numbers in the tank.
Remember, that when we make a mistake in this hobby, all we are out is financially related, but the seahorses can loose their lives.
Please do more research here and on the "org" before you go any further, and get the opinions of others as it definitely is a hobby with many approaches to success.