Most of the documents in a Bundle for a hearing will be A4 size, but you may have a few which are A3 size or larger. Generally the size of the pages in the Bundle should be the same as the originals but occasionally it might be different - for example if the original has very small writing, you might want to use a larger copy.
The documents in a Bundle should be arranged in logical sequence in appropriate sections, so a single A3 page should ideally be in the appropriate position in a volume of mainly A4 pages, rather than in a separate volume. This can be done by folding the A3 sheet in half and then folding the right hand half in half again like this:
Folding A3 sheets twice like this is appropriate if you have one or two A3 pages within documents which are mainly A4 . If, however, you have a document made up entirely (or mostly) of A3 pages then it might be more appropriate to use a separate large volume binder designed for A3 sheets rather than do lots of folding. Bear in mind that the judges, barristers and witnesses will have to unfold every folded A3 sheet whenever it is referred to at the hearing so if there are only one or two, the minor inconvenience of having to do that is outweighed by the advantage of having the A3 sheet in its logical place rather than separately, but if there are a lot of A3 sheets then a separate A3 binder is generally the better option.
Folded A3 sheets should generally be printed only on one side. Unfolded sheets can be printed on both sides.
One effect of inserting folded A3 sheets in this way may be that the bundle page number does not appear on the bottom right hand corner of the sheet as folded, in which case you should write in the page number in that position with a pen.
When you load PDFs you can add - A4A3 to the end of the file name to remind you that the document contains a mixture of A4 and A3 pages and that you need to print out the A3 pages on A3 paper when you come to print and assemble the Bundle. If, however, you have a multi-page document made up entirely of A3 pages (or mostly A3 pages with no pages larger than A3) then you would just add - A3 to the end of the PDF file name to indicate that all pages should be printed as A3.
The reason why it is easy to fold an A3 sheet twice and include it in an A4 volume is that the width of an A3 sheet is exactly the same as the length of an A4 sheet. It is not so easy to include an A2 sheet in an A4 volume and generally A2 sheets need to be in a separate volume from A4 sheets, either in a volume binder designed for A2 sheets or, if there are just a few A2 pages, perhaps folded twice in a binder designed for A3 sheets if there are a number of A3 sheets. The width of an A2 sheet is, of course, exactly the same as the length of an A3 sheet.