usability - How to resolve a multilevel sidebar menu where parent sections must show children AND link somewhere

Note: When reading this keep in mind we may have more of an information architecture problem than a menu usability one.

Suppose we have this menu:

Item 1              ............  Should link to Page 1 AND somehow show its children
    Item 1.1        ............  Should link to Page 1.1
    Item 1.2        ............  Should link to Page 1.2
    Item 1.3        ............  Should link to Page 1.3 AND somehow show its children
        Item 1.3.1  ............  Should link to Page 1.3.1
        Item 1.3.2  ............  Should link to Page 1.3.2
Item 2              ............  There is no Page 2. This should not link anywhere. Only show its children.

    Item 2.1  
    Item 2.2
    Item 2.3

Etc. with more items....

The challenge:

1. We want children and grandchildren items hidden by default so we need a way to show them on demand.



2. We dont want to use a flyout/hover interaction which our users have trouble with. We only want to use clicking.


3. Some parent items are pages themselves and so they must be linked to somehow. Other parent items exist solely to provide a kind of group title to encompass their children and show site structure but these parent items are not pages themselves.


4. User base: people above 40 and with little internet experience and sometimes limited vision/dexterity. They have problems with things you would not imagine.

I have thought of doing something like:

Link 1  [+]
    Link 1.1
    Link 1.2
    Link 1.3 [+]

        Link 1.3.1
        Link 1.3.2
Non-link 2  [+]
    Link 2.1
    Link 2.2

Where the [+] symbol would be an icon that shows you can open/close a sublevel. You would click on that to see children items but would click on the text to actually go to a page. I'm worried that the [+] icon would be too small to be easily clickable by our users.

Any alternative suggestions would be dearly appreciated as I have had this problem on 3 projects now and have never really found a solution I was satisfied with.

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Answer

I'm sorry to break it to you, but there won't be a solution for this if you're not ready to change the IA at all.

One (cheap and not very elegant) solution is to always move the content on the parent one level down and call it something like "overview" or "introduction"; like this when you click on a parent the sub-level opens and the first item of the sub-level is active. Not nice, but better than plus icons or stuff like that.

Hope that helps, Phil