At first during the very early stages in the late 2030s it was still considered but a silly fantasy made-up by the architect that both funded the labs and led the teams but the results that soon flourish into a new resort and treatment enterprise...
...that being said such a discovery had issues mostly in groups either opposed to human transformations or those that did yet insisted on one-way and oftentimes weaponized, none which the architect supported his discovery to benefit people through happiness that he had led the way in creating merfolk.
That's right. this architect had created a means of turning humans into merfolk and back. yet instead of selling their find off instead turned to an odd mixture of mental health treatment centre and water resort and didn't leave the teams' members and their families out for when the architect died he left control over the new business to them.
Now for visiting guests without prior connections the resort would merely look like a small-town size water-park with a few hotels or inns attached with people of various ages and ethnic backgrounds wearing oddly flexible yet usually colourful merfolk tails costumes entertaining the guests in various ways as to be expected with the only thing of note being that only they can access these exclusive areas via a tunnel system...
...in reality though these mermaiding performers are those both transformed and usually undergoing the mental healthcare side of this system. usually through interventions by concerned family members or friends to either chanced upon forums or talks with mental healthcare doctors with ties either knowingly or unknowingly to the now board of the resort, many are taken their to be transformed and spend time away from the stresses that prior to the interventions were leading to severe mental collapse... not to say that now and again they get those that discover this aspect themselves and request to participate in being merfolk.
The process while kept confidential for safety reasons from opposed groups to the resort's runnings and method usually involves a flu-jap style injection to the participant that renders then unconscious for about 4 days while their body undergoes the metamorphosis, the only still uncertain part being the colours the tails turn out and other officially considered cosmetic changes like the pelvic fins being belt-like or branch-like and if they get webbed fingers or ears...
...also during this process participants often undergo a form of mental conditioning, nothing super drastic only to make their minds more natural and accepting to being merfolk with all their human memories intact, to all intents and purposes until they are down to the last third (usually two weeks remaining) of their stay they are part of the merfolk pods in both body and mind...
...but for those in this final third this is also an important time of decision as once their mind is back to before the transformation yet often more calm and relaxed, this is also when the resort gives one of it's most important offers... the option to remain a merperson indefinitely and become a full time staff member of the place, most really choose to return but of those that did choose to remain by the 2060s a few were now board members of the resort.
Now there have been changes since the resort opened. originally the merfolk project was exclusively to adult woman but the staff maintaining the research soon improved upon the system to allow males to become mermen. a while after that and a number of families with children getting involved and read-in, the project soon expanded to all ages...
...however of course those under legal adult age required parental or legal guardian consent not merely to be transformed in the first place but also if offered the option to remain.
And speaking of children mermaids can get pregnant by either human men or merman and human woman can get pregnant from intercourse with mermen (though rape via merperson and human is extremely frowned upon by the resort's board so mutual consent is an absolute law here) regardless the children of such births are fully human with many of the sons and/or daughters of permanent merfolk staff members being among the children who are transformed.
Right now though, who is coming to the resort and under what reasons: