Subtemplates within blocks

I want to render the contents of a block in another file, like so
And then in showblock.tpl
Or whatever. Is this possible? It does seem to merge the contents of the file but the fields don't have any values, they just disappear.

Hello,

If your subtemplate is the same for all record, then you can do normally:
The subtemplate will be inserted when main template is loaded, so the full template will be ready for block merging.

Of course! I was thinking about it in totally the wrong way. Thanks a lot.