I'm a first home buyer looking to buy a property in Sydney. I have identified a house I would love to purchase due to a pre-existing granny flat that I could rent out as I live in the main house and will ease my mortgage payments. I've requested the contract, but can't find mention of this granny flat on it (and have had it reviewed by a solicitor friend of mine) and I've asked my conveyancer to request proof of a certificate of occupancy/council approval for the flat, but haven't heard back. I have been given the Sydney water pipe map from my conveyancer and I cannot see the flat on the map, but I can see the main house. Is it normal for granny flats built after the home to not be included on these plot maps? The flat is also built directly over the sewage pipe, which I know can be approved but don't know if it is common.

I should mention the property map for the lot states the address as 20-20A (indicating the granny) and the granny flat is advertised on the listing by the real estate, who have also performed a rental assessment for it. I'm probably being way too cautious but I'm just inexperienced with all this and I don't trust people haha