House with several manholes

[keai7]

We currently have our offer accepted on a 120 year old mid terrace victorian property and the building survey came back indicating that there are several manholes in that house. This led us to think that the neighbours drains converge at this property before leading to the main drain (would be interested to hear if anyone can think of any other reasons for the multiple manholes). We are waiting for the final report from the surveyor to see where the location of the manholes are.

Our concerns:
1. Does being the point of convergence for the multiple manholes indicate more potential problems with drain blockages (as opposed to if we had just 1 that serves our house)?
2. It being an old house, are victorian drains likely be at a crumbling point hence more potential problems ahead?
3. We are thinking of a major side and rear extension which would likely mean having this manholes in our new open plan living room. Are we crazy?

We were thinking of getting a drain specialist to have a look of the reason behind all these manholes and if our suspicion holds true, we were wondering if it's worthwhile buying a house like this with extension in mind. Would you buy a house given the above?

[keai7]

Thanks all for sharing your thoughts and experiences. Confirms our concerns. Feeling sad to walk away from a property which took so long to find. If only the drains weren't120 years old with risk of crumbling...than again, as pointed out, it could be neighbours causing blockages and I don't want to be rodding sewage in our brand new living room every so often.