How to identify users across subdomains?

Hey,

I have an issue identifying users in subdomains. I know that the topic has already been raised a couple of times and I have already read this article, but I can't apply the solution suggested there to my problem, because there are  no <a> elements or links that I could enrich with the _kx parameter. The routing is done via js functions.

What I have tried so far is rewriting the _kla_id cookie for the subdomain or primary domain when it was already set. This seem to work but I am a little worried about edge cases that I may have not covered. Any advice on this?

Is it possible to persist the exchange_id other than attaching it to a link and then use it in another identify call on the next (sub)domain? 

Thanks,
Tristan