The point is not to utilize the loop holes. Siachen was never considered in scope of discussion because nobody bothered that area before 84. This is the statement from Shimla pact:-
"(ii) In
Jammu and Kashmir, the line of control resulting from the ceasefire of December 17, 1971, shall be respected by both sides without prejudice to the recognized position of either side. Neither side shall seek to alter it unilaterally, irrespective of mutual differences and legal interpretations. Both sides further undertake to refrain from the threat or the
use of force in violation of this line."
Now if you don't think Siachen is part of J&K or Siachen should have been discussed without war then thats just our perspective.