ArcGIS Modelbuilder: Merge features from same layer into one feature

Question

How can I merge two features from the same layer into one feature when using the Model Builder?

Outside of the model builder, this can easily be done with the Edit Tool. How can I make the same process work in Modelbuilder?

Also, is there a way to automatically tell Modelbuilder to chose the Feature with the lower Value of Field-X to be the "Parent-feature"?

I work with ArcGIS 10.1

I aksed the question also on gis.stackexchange: 
ArcGIS Modelbuilder: Merge features from same layer into one feature - Geographic Information Systems Stack Exchange

ChrisDonohue__GISP · Answer

Not sure if this was already mentioned as a potential solution, but I'll throw it out.  This will work if each feature that needs to be merged to another is be assigned the same value in an attribute field.  The result of this tool will be a new (dissolved) layer as an output.  For example, if I have several polygons that are coded "LDR" and several that are coded "MDR", they can be merged by running this tool, with the result being a "LDR" polygon and a "MDR" polygon.

ArcGIS Help (10.2, 10.2.1, and 10.2.2) - Dissolve (Data Management)

Chris Donohue, GISP

AbdullahAnter · Answer

this question was asked before.

Look to the answers in this links:

https://community.esri.com/thread/109428

https://community.esri.com/thread/176035

PankajJamwal1 · Answer

Were you able to find a solution for this? I also want to merge two features from the same Feature class into one feature on the basis of Unique identifier.