Not sure if I understand your goal correctly...
One of the methods could be:
Create new document of desired page size. Place your original indd file here, page by page. Resize them to fit (this could be automated in some manner).
This new document is good for exporting pdf's or such. All content edits, if needed, should be done in original file. Save file, update links... Exactly the same procedure as with any other linked objects.
I am new to Indesign, problem is I am designing a banner (1x2m in size) and made my original size 2,5mx5m!!
I placed all the photos on there in the format I wish only to realise the size is way too big.
I tried simply changing the document size but then all my photos are not sized along and I have to redo it ((
Ah, I see...
Well, your case fits exactly. If I were you, I would go that way I described above. It is fast, reliable, and it works. Just try...
How do I "Place your original indd file here, page by page"
Since your original file has only one page (right?) 'page by page' is irrelevant.
Place exactly as you do with your pictures: File>Place - select your "too big" indd file... Further actions are pretty intuitive, I believe
Sorry - not working
Imports whole layout as a singular image and the individual photos are no longer select able:((
What am I doing wrong?
You're doing all right. As I said, all edits should be done in original file. Your new file is dedicated just for RESIZING - easy and reliable.
It's like an image now... When you place psd file in InDesign, you don't expect have full control on its content here, right? You do edits in Photoshop and update link. Here's the same workflow - do edits in original file (your 2,5x5m indd file) and update link...
Oops, that is the original problem, the original file is too big for the Mac to handle. I had to size the photos to that size in Photoshop to ensure no pixilation, that however crashes the mac........
Any way to save the empty frame as a "template" then I can maybe create a smaller doc and have the frame template on it?
I think I got lucky, used "Liquid Layout" - Scale - change document size and it scaled all the frames!!!!
Thanks for all your help:))