Hi Barb. Thank you for your question. You may have opened a small can of worms.
Item 11 on page 11 of our go-to document, Guidance for Transcription Using the Nemeth Code within UEB Contexts, says "The opening Nemeth Code indicator and the Nemeth Code terminator should be placed on the same page with part of the expression to which they apply." It doesn't specifically say "print page". I see no problem with switching to Nemeth Code at the end of the UEB paragraph, before the page change indicator.
Personally, if this is a worksheet for a young reader, it might be friendlier to place the opening switch on the very next line
after the page change indicator. (Another option would be to wait to switch until after the first identifier "22" which would be in UEB.)
In any case, a switch indicator does not replace a blank line. The line before item 22 will need to be blank.
Hope this helps.