You need to look at clause 83.1 and 83.2 which covers Indemnities. As far as you are concerned, the other Defect is the Employer's risk, but they have presumably passed it on in the same manner under the contract with the other Contractor.
If the amount of work to dismantle and re-assemble for the other contractor (if your Defect did not exist) would be exactly the same as for your Defect (if the other contractor's Defect did not exist), then liability would be split 50/50 ... easy !
However, the real world is not like that, so split the common elements of dismantling & re-assembling 50/50, then each covers their own unique elements. That's financial liability as if you were paying a third party to do it, but I assume between the two contractors you have two figure out who is going to do what.
Finally, you are correct: this is NOT indirect/consequential loss.