Is it possible to increase Samsung's limit on contact merging?
It is, if you have root Access.

Found the following solution on l0uy blog:

Open /system/csc/others.xml and add the following child to the &lt;FeatureSet&gt; parant:

&lt;CscFeature_Contact_SetLinkCountMaxAs&gt;30&lt;/CscFeature_Contact_SetLinkCountMaxAs&gt;


The 30 is the limit, how much contacts you will merge. choose what you want.

Works fine on 4.1.2.