Yes, and yes
The restriction here is that the first plant in your list has extra significance (If you are using the Alphabetic plants list option - I think you are)
Add a photo for your first plant.
Once you've done that, a More button appears when that plant is selected.
Click More.
You can add more Plant Photos, and more Garden Photos.
Heres the rules:Lets say you add 3 of each.
The 3 Garden Photos will sit sequentially above the plant photos.
You can shuffle the garden photos up and down
with respect to each other (these shuffle buttons only appear when you've more than one photo linked to a plant)
You can also shuffle the plant photos up and down
with respect to each other You cannot move plant photos above the garden photos which are linked to that plant.
Having done that, the garden photos linked to the first plant will appear just after the Introduction, per your intention.
If you subsequently add a plant to the list which is alphabetically before your first plant, then it goes above the garden photos linked to what WAS the first plant originally.
You would then need to unlink the Garden Photos from the original plant, and link them to the NEW first plant in the list.
I could do some more work on the program to allow users to shuffle the Garden Photos up and automatically link up to the NEW first plant, but (ahem) that might cause headaches
The above rules apply anywhere in the list, of course.
Advanced options

::: (Headaches guaranteed

)
You an create groups (look for option in Initial screen (GA032S01)
When you go that route, all plants can be shuffled into any desired order.
The following is an example:
http://www.ideasforgardens.net/botanic-gardens/belfast-botanic-gardens/Note how I have a garden photo as first in the list, just after the intro.
If you want to try that, I suggest you create a new review and play around with it.
Don't upset that 1053 (currently) masterpiece!!!
Love the new Review text!!
Now thats when this project REALLY starts to work. I value the reviews by experienced gardeners very highly.