M&A migration for SEO - going badly, need some advice

Apologies in advance - this is going to be a long post, but I'm in need of some advice...

We (Erobella, an international escort directory) recently purchased a UK competitor, adultseek.com, and migrated it into the /uk/ subfolder of our domain.

Prior to implementing 301 redirects, we went through a BIG exercise of mapping (in Excel) all of their landing pages with ours, and then 'routing' our landing pages onto their URLs. So, for example:

http://www.adultseek.com/gb/escorts/bristol (the competitor site)
showed (for a few days) the exact same content, <title>, <h1>, etc as
http://erobella.com/uk/escort/bristol/ (our site)

We did this to ensure that when it came to the redirects, we were redirecting landing pages with near 100% equivalence between the two sites. In the past that technique has worked pretty well for us, and seems to transfer much more power than standard redirects.

We only kept this routing live for a few days to avoid running into any cannibalisation problems, and used urlmonitor.com to quickly force index everything.

Then we implemented the redirects.

This all happened at the start of September.

Since then, we've seen some REALLY strange behaviour in the SERP's (see attached), including:

• Some erobella.com pages are popping in and out of the SERP's on a daily basis.
• Some erobella.com pages have dropped out of Google altogether.
• Some erobella.com pages have had a boost in SEO.
• Google is continuing to hold adultseek.com pages in its index, even though (according to GSC) it has recrawled them and seen the 301's.

Basically, no consistency at all.

We've done everything we can think of here - double checking 301's, manually re-submitting competitorwebsite.com pages to GSC that are still in the index, etc. But we're running out of ideas.

Have any of you guys seen something like this in a similar M&A domain migration before, and if so what would you recommend? Just sit and wait for Google to sort its shit out?

I’ll literally take any suggestions y’all can throw at me.

I'm not understanding the question, or what you need advice on.

I also don't understand what you mean by "routing" and I think this is where your problems might come from, even if this has worked for you in the past. The only way I know of to make the contents of 1 site display on another site is via 301 redirects. Maybe I'm not too technical of a person (which I'm not), but I genuinely don't know of other methods of achieving what I think you want to achieve, so I think you should have stuck to the good 'ol 301s that we know work.

And yes, when you confuse the googlebot it tends to behave chaotically

I don't think there's anything you can do but wait, but that's assuming that everything's right with your site, which I have a feeling that it's not.

I would run a FULL site audit with tools like Screaming Frog (or any other good auditing tool of your choice) as I have a suspicion that you might have screwed something up in the migration process (problems always occur during migration of sites with multiple pages, or which have technical issues prior to migration). So, run a full site audit and see if you detect any big technical issues and fix them if it's not too late.

Additionally, I would also compare the pages on your site that lost rankings with the ones that gained rankings, maybe you find stuff that 1 of the 2 categories of pages did / did not that the other category of pages did / did not (hopefully I make sense)...

Last but not least, please - for the love of God - stop exposing your sites on the biggest SEO forum on the planet that google keeps an eye on. It's not once that sites that have been exposed have totally tanked within 1 week of being exposed here, so be a little more private with your money makers