They have reliable birth control, but they want babies in spring more than the rest of the year.

Oh, huh. Mermaids want new babies less when they're naturally infertile but that's because they already have small children. 

Oh, yeah, Amentans who actually have a baby or even a one-year-old are usually fine with being in spring (though the sex drive boost can be separately tiring). It's just they don't want to live that way all the time even when they don't have a baby.

That makes complete sense. 

They are hoping to have fewer empty springs now that they can settle more planets! The merpeople's planet probably has too-short years, but they'd like to set up a camp for volunteers to see if any of them reseason.

Sure! The merpeople aren't using the land for anything, the Amentans are welcome to it. Although they probably want to talk to other merpeople countries before settling land adjacent to them. 

Yes, that makes sense! (Hey, merpeople internet of other countries, should they send more landing parties or talk to them online or what?)

(Talking online is acceptable but more landing parties would be preferred.)

They can send more landing parties! If there are merfolk countries not near any land that will be more difficult.

There are merfolk countries not near any land. One of them isn't close to any land but is pretty close to the surface and could build a floating platform to land on if the Amentans give them specs for what kind of landing terrain they need. 

The platform needs to hold a ship that weighs yea much and applies yea much force on landing.

They can do that!

Other merpeople countries are working out treaties with shore-bordering merpeople countries to send embassies to the shore. 

Tapa sends lots of emisarries in all requested directions. They want to be friends with all the merpeople.

All of the merpeople want to be friends with the aliens!

Some merpeople countries are similar, and some are very different. This one considers it impolite to discuss The Abominations in polite conversation. This one will only let you have biological children if you've raised a certain number of adoptive ones first, consent to reductive abortion, or have performed so many years of military or civil service, and removing the birth control implant of someone not approved for childbirth is a sterilizing offense. This one assigns each clutch a predicted eugenic value and requires that adoptive parents choose from the top five scored clutches currently at their local creche. 

These all seem reasonable, though it does mean the Amentans will have to get their information about Abominations elsewhere.

This one was experimenting with reducing clutch numbers by doing conceptions exclusively via IVF in one city but their data was confounded and a huge public uproar was caused when it transpired that one of the doctors working at the IVF clinic was secretly replacing sperm samples with his own. The doctor was executed but they had to discontinue the program because nobody trusted it. 

Oh no! What a sad story. Similar things have happened in Amenta; they have gamete donation charities aimed at mild springs and sometimes somebody unscrupulous messes with them.

That's terrible! It's always so awful when someone decides to be selfish and endanger the public good for their own benefit. 

They're agreed! It would be funny if they wound up running the charities for each other so no one biologically compatible would be handling the samples!

...Huh. That would be an idea. 

It would! It doesn't seem like an urgent first contact priority but maybe in a year or two.

Maybe! It could be tricky and they'd have to run some cost-benefit analyses but who knows. 

So the problem with reductive abortions is that they sometimes cause miscarriage, right? Have they tried things that seem obvious at a first pass, like coming up with some filler biomaterial to stick in there, artificial hormones to mimic the profile of someone more numerously pregnant, performing the abortion late enough that the remaining eggs will be viable even if ejected, using a slow poison injected into some of the eggs that will leave them alive for most of the pregnancy so they don't rot in there but not have them viable at the time they're laid...?

They haven't found a filler that both will expand at the correct rate to trick the body into thinking the "eggs" are still viable and won't be rejected by the immune system. Artificial hormones wouldn't work, the hormones don't change depending on the size of the pregnancy. The other two have been tried but the second doesn't reliably work and the first one causes health issues in the ensuing babies. Not huge ones, just regular prematurity issues, but enough that people wouldn't accept it at scale. 

Have they made any attempts at uterine replicators?