Merge 2 JSON strings??

I have 2 JSON strings, which contains varying nested objects.  I need to merge the two strings into one string, maintaining all the hierarchies.  I suspect I need some sort of recursive regular expression, but this is outside my area of expertise.

Any help is greatly appreciated.

For example:

var json1 = { "root": { "Company": {"Name":"CompanyName", "Address":"MainStreet"} } }
var json2 = { "root": {"AnotherObj": { "Property":"Value"}, "Company" : {"Phone":"604"} }

var merged = { "root" : {"Company": {"Name":"CompanyName", "Address":"MainStreet", "Phone":"604"}, "AnotherObj": {"Property":"Value"}} }

So, The fields of the company object from the second string have been appended into company fields of the first string.