hi Knowsitlike and welcome. I see you have just joined up, and here on this great forum is the place to get all the advice and support you wlll ever need!!
With regards to the original contract, no.. clauses remain as they were at the start. I forgot to include one for the termite control but my builder did it anyway, at no charge as we had spoken about it at one of the meetings pre-contract.
There have been a few items not in the contract that we have done - the duct bank under zone 2, the external window detailing (i have not yet posted those pictures), and additions to the budget for, say the wall and floor tiling, where we changed out minds nearer the time. There has not been too much of that though.
We wanted to retain control of the kitchens and bathrooms - others might want all that written in to the contract - but by keeping it separate, we keep 100% control of what goes in. No compromises. We might still have k.pot build part of the kitchen, not decided yet. What we did put in was the labour part in the contract- whatever we buy he fits, if required. We will definitely use that clause for the sanitary ware, definitely not for the AC, and maybe for the kitchen!!
Keep your options open