Attach a picture to a symbol

I would like to attach a picture to a symbol. Is this possible?

This is possible. Symbol notes will "stick" to the symbol. (If you change the symbol date, the note will move right along with the symbol).

Add a picture either by inserting a picture from a file or by pasting a picture you have copied to your clipboard.

Using the arrow tool, right-click the picture.
Choose Properties.
In the Automation Tag field, enter a name for the picture. (Like MyPicture) and click OK.

Using the arrow tool, click once on the symbol. The toolbar changes to Current Object: Symbol.
Select the Notes tab.
Enter the following into the symbol note space: <Image tag="MyPicture"> (no spaces around the =)
Press the Apply Text Changes button.
In the toolbar, under Symbol Note Display, be sure that Display Note on Schedule is checked.
By default, you may have a background color and frame associated with your symbol note (as shown in the example at the top of this page). Use the toolbar to change these settings.

Using the arrow tool, click once on the symbol.
Use the directional arrows to reposition the symbol. Hold down the Shift key while using the arrows to move the symbol note faster.

If you only want the picture to appear with the symbol (and not anywhere else on the schedule), you can move the picture to an empty or non-existent page:

Using the arrow tool, click once on the picture. The toolbar changes to Current Object: Graphic.
In the Page section, for Current Page enter a number which is greater than the number of pages on your schedule (for example, if you have a 2 page schedule, enter 3 or 4)
Click Update Page. The graphic will still be part of your schedule but will not be visible. The picture can be managed via Manage Pictures on the Tools tab.

Milestones Professional Help Topics offer additional information about symbol notes.
When you move a symbol which has notes, the notes will move relative to the symbol. If you have repositioned the symbol to the right, for example, then when the symbol is moved, the symbol note will remain to the right.