Orphan book titles when beginning next book on last page of previous book

How do I avoid orphan book titles when using the begin next book on last page of previous book option? I have tried a variety of Page Full Factors, but none resolve the issue. Is there a way to manually force a page break when needed or to ensure that the title is kept with the following text?
Two other related questions: Is there a way to remove the two horizontal lines between the books? Is there a way to reduce the space between the book title and start of the chapter. I’ve adjusted the Space After Factor for the \mt style, but it doesn’t seem to have an effect.

Just so I understand you correctly, are you saying that you’re getting somethign like this:

| this is supposed to represent the  |
| last verse of text.                |
|                                    |
|         The Book of Job            |

If so, then we’ll need an archive (see the help tab), because that should never happen.

There should only be a single horizontal line between books. It is actually a line separating double and single column text. I got that far digging a couple of weeks ago, but I’m not entirely sure why it started getting triggered twice a few months ago, and haven’t had time to dig into it further.

At the moment there’s no way to turn it off, other than not beginning the new book on the last page of the old one.

Yes, that’s it, David. I’ll send an archive. Thanks for looking into it.

I couldn’t get it to work in my testing, but I’m assuming you keep the “The Book of Job” from breaking immediately after it with a \sethook and a \penalty10000 or something like that. David should know.

What was happening is that the code that tries to ensure that the document starts a new page when the old one is (say) 65% was getting fired twice: once just before the title, and once after. If the page was 64% full before the title, then it put the title in and then decided ‘oops, there’s not enough page left to start two column mode now’.
I’ve applied what I’m sure is a bit of bodge-job: if it’s starting 2 column body text then it now only insists on enough space for a couple of lines of text. There must be a better way, I’m just not sure what that is at the moment.

Thanks for digging into this and for the initial fix.

The initial fix is in 2.3.2.

Great! Thanks for this and other fixes.