Plugin inserts content above WP header, help please

Can anyone help me please?

I have a plugin which is supposed to insert content from my genealogy pages into a WP page. (it also permits integrated login and themes)
The login appears to be working and the theme integration too.
However, the content is being rendered before the WP header and I cannot see why.
Can any of you experts take a look for me please?
The problem can be seen here:

Many thanks