How to connect two .tpl files to php?

Question

DLE

In general, the question is this. About DLE. Template files on tpl. Index.php and index.tpl are responsible for the main page, search.php and search.tpl are responsible for the search file. In general, I brought a search filter to the main page, and I don’t want to transfer all the $tpl->set('{functions}' functions to index.php ... How can I include the index.tpl file in search.php so that in index .tpl did all the functions written in search.tpl work?