[C#]
// Set up the CRM Service.
CrmService service = new CrmService();
service.Credentials = System.Net.CredentialCache.DefaultCredentials;

// Create the target for the request.
TargetMergeAccount target = new TargetMergeAccount();
// EntityId is the GUID of the account that is being merged into.
target.EntityId = new Guid("2B951FBC-1C56-4430-B23B-20A1349068F3");

// Create the request.
MergeRequest merge = new MergeRequest();
// SubordinateId is the GUID of the account merging.
merge.SubordinateId = new Guid("AD618DB2-F0DB-4A6A-8C4B-2F2213EAA38E");
merge.Target = target;
merge.PerformParentingChecks = false;

account updateContent = new account();
updateContent.address1_line1 = "54321 NE Main St";
merge.UpdateContent = updateContent;

// Execute the request.
MergeResponse merged = (MergeResponse)service.Execute(merge);

[Visual Basic .NET]
' Set up the CRM Service.
Dim service As New CrmService()
service.Credentials = System.Net.CredentialCache.DefaultCredentials

' Create the target for the request.
Dim target As New TargetMergeAccount()
' EntityId is the GUID of the account that is being merged into.
target.EntityId = new Guid("2B951FBC-1C56-4430-B23B-20A1349068F3")

' Create the request.
Dim merge As New MergeRequest()
' SubordinateId is the GUID of the account merging.
merge.SubordinateId = new Guid("AD618DB2-F0DB-4A6A-8C4B-2F2213EAA38E")
merge.Target = target
merge.PerformParentingChecks = false

Dim updateContent As New account()
updateContent.address1_line1 = "54321 NE Main St"
merge.UpdateContent = updateContent

' Execute the request.
Dim merged As MergeResponse = CType(service.Execute(merge), MergeResponse)