Picture-In-Picture Subtitles Problem?

[Damage Inc.]

I have a bunch of films on BD, but I didn't really check out the PIP-features on some of them yet.
Well, I did on one, but I found that it apparently doesn't switch the subtitles automatically.
Like, you're watching the film with any type of subtitles and you turn on the PIP,
then the subtitles of the film just play through the PIP.
Which is twice the issue, it shows the wrong subtitles and it's placed on top of the PIP-video.
Shouldn't it switch the subtitles to the PIP-type when you activate it,
just like the PIP-audio activates when you turn on the PIP-video?...

Doesn't seem like it's impossible, but perhaps an overlooked feature?