Can you link a block attribute to a custom property?
Yes.
There is no 'Link to Property' button to use within the Attributes window, but it accepts the values generated by it elsewhere.
I have a common on most of my drawings. It is a Connection label, and a legend is shown on the sheet to correlate what it is. Its value could be A, B, C, or A1, A2, A3, or anything that the project manager or client desires. In my work, this could typically be suction, vent, drain, and discharge connections. The value shown is an Attribute within the block. I normally paste the block where it is needed in every applicable view, and manually edit its attribute value. I also normally set this in the beginning of a project, and it usually does not change. Oh, but it can. Life IS change.
Today I am asked to change A, B, and C to X, Y, and Z, which is a strange request. All the same, I prefer to Design for Change (to use 's terms). I wondered if you can refer to a custom property for a connection type. To test it out, I made ConnSuction, ConnVent, and ConnDisch custom properties in my drawing (which ought to be in the assembly to refer to in any drawing created by it) and populated it with the new values.
Then, in an unassociated bit of text annotation, I created a parametric link to that custom property using the Link to Property dialog within the Note feature manager. Then, I right-clicked the text and Edit Text in Window. I cut the text string generated by Link to Property. Then, I selected the block for connection A, and edited its attribute by pasting the Link to Property string. To my delight, it works. In my context, referring to a Property within the drawing, its pasted value was $PRP:"ConnSuction" . I then edited attributes across the drawing views to refer to same or similar. Now, I can change a property, and the referenced values in all referenced places will update accordingly. To me, this is the most powerful use of custom properties within drawings: to create one place to edit something located in many places throughout the drawing, usually across many pages and potentially with a cumbersome large assembly.
The next time I update my , I'd like to include common connection types and values. As needed, it can be expanded to suit, or disused if unneeded. Then, I'd also update my Customer Connections list template block (which also includes the symbol blocks) to refer to properties. It will be one more thing I can set up initially and control parametrically.
Maybe this can help you if it is applicable to your work in some way, likely in ways different than my own.
A Link to Property button could be added to the Attribute dialog box. It is text and can benefit from Note controls.