Cross Cluster Search without modifying existing query

Hi,

I have two clusters one is "Cluster A" and other is "Cluster B".

To perform search on cluster A, I am using below query:-

< GET /test_index/_search
{
"query":{
"match_all":{}
}
} />

But to search across multiple clusters, I have to modify query to this :-

< GET /test_index,remote_cs2:test_index/_search
{
"query":{
"match_all":{}
}
} />

Is there any other way to search across across multiple clusters without modifying my first query ?
Because in this way i have to make lot many changes in the queries which i want to avoid.

Could some one please help me with this, i can provide you more information if you need.