Hi Nick
what you suggest is what I did in the first place and what failed to do what I need.
There seems to be a fundamental misunderstanding regarding my products:
******* the T-shirt is the WRONG EXAMPLE! **********
Please let me try to explain with an hypothetical example:
Imagine a webshop. The product image shows a Mercedes.
You can buy it:
- as a toy car (children can sit on it an ride it). Variations: made of plastic, made of wood.
- as an automobile. Variations: power of the engine.
-> If you want to buy the toy car, it does not make sense to make it depend of the selection of an engine - an engine is not a variation of the toy car.
-> If you want to buy the automobile, there is no point in making it depend of the selection of the material, as material is not a variation of the automobile.
************
The products I offer are printed photographs.
You can buy them:
- as a card (a print of 11x17cm, glued on a double card (typically used as greeting card). Variations: the color of the underlying double-card.
- as a large print (some call it a fine-art print) to frame and hang on a wall. Variations: the size of the print.
"Card" is a product on its own and "large print" is a product on its own.
"print size" is not a variation of "card", and "color" is not a variation of "large print"
The variations of "cards" and of "large prints" are mutually exclusive.
What they have in common is the digital photograph they are printed from.
The image on the "Card" is the same as on the "Print" product.
"Cards" and "Large Prints" are both prints, but different products nevertheless!
Please see: http://www.wp.fotowalther.ch/?product_cat=demo:
I photographed a sample of the 2 products and assigned them to a menu item "Demo" to show my point:
"Photo" is the original digital photo from which the products "Card" and "Print" are created.
To me the "Photo" is the parent-product (not for sale, only for display), "Card" and "Print" are the child-products (i.e. the actual available 2 products).
However:
- The child products must not show on the same page with the parent-product.
- On the product details page the grid should not spread over the entire width of the container
Setting it up as a grouped product IMHO is not a mistake, but the only solution I know of, so far, that produced the result I have in mind:
When you select an individual (parent) photograph
- you are presented with the whole range of available cards and large prints made from it
- you see the price of any of these individual items
- you can produce a one-step order with any type and variation of the products in any quantity you like
Example: you could buy 3 red cards, 1 blue card and 1 large print 40x60cm from the same photo.
The shopping process is as follows:
a) select a category (Travel, Animals; Flowers)
b) browse through the images in this category
c) select an individual image
d) select the product type (how you would like the image to be printed): as a card and/or as a large print
e) select the variation and the quantity of the product
e) add the product(s) to the cart ...
**********************
Unless you have a better solution I would be more than happy if you or any staff member could help me with my 2 questions (see above).
It's killing me because without I cannot continue building my website (the shop is the cornerstone and serves as gallery AND shop).
I'm really sorry to cause so much trouble. I hoped someone could simply give me a piece of code I could add to the quick CSS or the custom CSS or a source file.
I'm fully aware that it must be difficult for you to understand, because key words such as "product", "image" and "prints" have different meanings in the same context.
Thanks for your patience
Bruno
************
P.S.
I'm trying to replicate the functionality of my existing shop (Joomla/Virtuemart) of which my version is no longer supported and the migration to the new version completely failed. So I want to rebuild the shop with WordPress
You can see an example of the existing shop and its functionality here:
http://www.fotowalther.ch/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=1088&category_id=17&option=com_virtuemart&Itemid=99
Create a new thread and tell me what problems you are encountering and what you want to know. 
There is no step 3 :) 
