How to preserve shared boundary in multipart polygons

[JulieLuetzelschwab]

I need to preserve the shared boundary between polygons but make them a multipart polygon.  Dissolve with the multipart polygon checked still dissolves the shared boundary, and only makes one multipart polygon with separate polygons if they are not adjacent and sharing a boundary.  Union also dissolves the shared boundary.  The attributes for the adjacent polygons are the same.  There are 100s of polygons in this layer so I don't want to use editing tools.  I am hoping there is a Toolbox tool that will do this.  Any help is appreciated.  Thank you!

[DanPatterson]

shared boundaries will be removed if dissolving or aggregation by an attribute.

Perhaps you could explain why you want to make multipart shapes?   If you have a need to simplify a data structure to minimize duplication of attributes, you can simply keep your attributes separate and use a join when you need to bring attributes back to the geometry

[JulieLuetzelschwab]

We need to show total acres for the multipart polygons and the users of the data want to see the individual unit boundaries.

[DanPatterson]

You will have to maintain a geometry file which just contains the individual boundaries if that is paramount. 

If you haven't done the dissolve yet, then you can get a statistical summary on an aggregated basis. 

Is the aggregation based on ownership? crop type? 

Any details would help

[JulieLuetzelschwab]

Ok that's what I thought, it isn't possible to maintain a shared boundary with multipart polygons.  We can manage without it and maintain 2 separate layers if they need to see the original boundaries. Thanks for your help.

[DanPatterson]

No problem

[Luke_Pinner]

Multipart polygons cannot share borders. From the help:

Keep in mind that parts in a multipart polygon are spatially separated. They can touch each other at vertices, but they cannot share edges or overlap.