Easyway to do this is to make up booklet using blank pages, fold as A5 and number the bottom of pages, the booklet can then be seperated out to see where the page numbers fall in relation to each other.
But you have a problem if you want to just fold the a4 to a5 to saddle stitch (staple) because you would need to have 32 pages instead of 30 so would need to bind using another method -
when using this method of printing a booklet (its called perfecting) the opposing pages always add up to one more than the total number of pages.
to simplify a 4 page booklet - page 1 and 4 is printed an one side add up to 5
and pages 2 and 3 printed on other side also add up to 5.
As you say, you will have four pages per sheet, so you need to use a multiple of four pages (32 in this case). If you set it up as a Side Fold Booklet – noting that you have to choose Booklet, not Book – PagePlus will sort out the page order for you. For printing to PDF, be sure to tick the 'Impose Pages' checkbox on the General tab of the Publish PDF' dialog.
My pages start at 1 and end at 25 if I add a page total is 27 (Not a multiple of 4)
It is to be printed as A5. If i go to the first page Pageplus 11 displays a single A5 page; go to the second page it displays pages 2 & 3 all up to the last page 24 & 25.
The print preview shows the pages as :-
1st page 4 & 1 together
2nd page 2 & 3 together
3rd 8 & 5
4th 6 & 7
5th 12 & 9
6th 10 &11
7th 16 & 13
8th 14 & 15
9th 20 & 17
10th 18 &19
11th 24 & 21
12th 22 & 23
13th nopage number & 25
I would have expected the first page to contain Pages 1 and 25 at least
I cannot say as I understand the reason for the difference myself. Why would anyone want to print book sections of a single sheet? There should be an option to print sections of 8 or 16 pages for perfect binding.