How do I split a text message "conversation" in two?

[Mooonlight]

On my Samsung S4 Mini (Kitkat 4.4.4) I have a couple text message "conversations"/threads. One of them has become excruciatingly slow; slow to open, slow to send new messages, and slow to close. The other conversations work just fine, so I suspect the slowness is because this one conversation contains lots and lots of messages (like a couple thousands).

I'm using the default Messages app, which I quite like and would like to continue to use.
And I don't want to remove the old messages from my phone, I want to keep them there and have easy access to them.

Is there some way to split a conversation into two? Or to end/lock the current conversation and start a new one with the same person?
I have tried to change their name among my contacts, but that didn't help; the Messages app seems to care about the phone number rather than the name.

 

[B. Diddy]

Welcome to Android Central! I don't believe that's possible. You could consider backing up your SMS messages using something like SMS Backup & Restore, but the stock messaging app just isn't designed to store thousands of messages forever.

 

[Rukbat]

SMS B & R can actually be used to split an xml file (which is what an SMS is) into as many pieces as you like. Open a copy of it (never work on the original at first) and see where you'd break it into individual messages or blocks. Once you're sure of what you're doing, keep a copy of the whole file somewhere (other than on the phone), split the message up, delete all your messages and read in your "cut up" block. You should end up with as many messages as you made blocks. (Keep most of the messages [a few thousand is FAR too many for a single thread]). The ones you don't have to refer to all the time you can leave as a single SMS block. and use SMS to Text if you ever need them in text form. (I have a thread going back 2-1/2 years, and it has FAR fewer than a couple pf thousand.)

As for the name/number, every text has a number attached to it, not every one has a name that makes sense. That's why they're kept by number. (Sometimes that just drives you nuts - 500 messages from your power company? But it's how it's always been done.)

 

[Mooonlight]

Many thanks!

In case someone gets similar problems and wonders... I've finally tried this and it almost worked.

I used SMS B & R to backup my messages; the thread I wanted to split into a separate file and the rest in another. Since MS Excel could open and safe the files properly, I edited the one I wanted to split in Microsoft XML Notepad 2007, which was an excruciatingly slow process but worked well.

However, removing messages from my monster thread of nearly 14.000 messages turned out to be difficult. Or rather impossible. I tried both deleting the entire thread and deleting one message at a time, but neither worked. I tried deleting in both the stock Messages app and in SMS B & R, but when nothing seemed to have happened after 14 hours I gave up and restarted the phone.
So eventually I ended up doing a factory reset. Then I restored my backup files with SMS B & R. Out of totally 16.000 messages about 200 failed, and of course I have no idea which. But I could have been worse off...

Thanks Rukbat for your help!
I think, in the future, I'll try to split my threads before they get this huge...