Currently, bitcoin must be redeemed by providing input to a script which results in the required output.  This causes the attached amount of bitcoin to become available for use in the outputs of a transaction.  Is there any work on creating a shorter "transaction" which, instead of creating a new output, points to (creates a virtual copy of) an existing (unspent) output with a larger amount attached to it?  This would invalidate the smaller, earlier UTXO and replace it with the new one without requiring the earlier one to be redeemed, and also without requiring the original script to be duplicated.  It is a method for aggregating bitcoin to a UTXO which may otherwise not be economically viable.

The idea is that there already exists a script that must be satisfied to spend X1, and if the owner of X1 would like to have the same requirements for spending X2, this would be a transaction that does that using fewer data bytes.  Since the script already exists, the transaction can simply point to it instead of duplicating it.

This would also enable the capacity of lightning channels to be increased on the fly without closing the existing channel and re-opening a new one.  The LN layer would have to cope with the possibility that the "short channel ID" could change.

Dave.