The survey return indicates that a wall mounted CBT , and therefore cable on wall ( and the potential complication from that ) was not the proposed method , so the installer did actually do the correct type of installation, the survey note for wall mounted CBT is different to the ‘built to curtilage’ one , ( although the exact term escapes me ) and would include a ‘potential wayleave’ note , advising the installer to knock on doors if a cable had to pass over a third party’s wall .
As far as using the now existing CSP on your neighbours wall for yourself , and potentially the two other neighbours ( so four addresses in total ) , it kind of depends,
if each of these addresses were provided with their own ‘Toby box’ in the footpath, so four small toby boxes , then four separate CSPs ( one on each address ) would be fitted assuming at some point all addresses ordered FTTP , but it’s also possible there could be two medium Toby boxes , so one Toby per pair of houses , but still potentially 4 CSP , as two ‘cables’ can leave a medium size toby box ( officially only one cable in a small Toby box )
You could check the footpath, how many toby boxes have been provided and where they are located in relation to the individual units within the terrace , is it two medium Tobys placed mid point between two pairs of the addresses or four small Toby boxes , one outside each address , or even just one Toby box mid point of the entire terrace that’s already been trenched to the existing CSP, with a view to cable all four from one CSP .
FWIW , if the existing CSP is located conveniently for all properties, and it’s known that there wouldn’t be any objections if four individual cables ran from this point ,( one to each property ) , there is a special cable ( called an X cable ) that has four individual fibres inside it ( in a single outer jacket ) , it has four connectors , so can utilise four ports on the CBT , if that were used on your neighbours install ( not that likely TBH ) but there would already be useable fibres at the CSP , that just needing plugging up at the CBT and a cable from the CSP to each property in the terrace, so basically the cable to your neighbours CSP is the only cable needed back to the CBT , and is already to provide service to you and 2 others , but as stated I doubt this was supplied .
If it wasn’t an X cable , its no big deal to run more cables from the CBT via the appropriate Toby box to either the existing CSP or to a new CSP , but the survey note suggests a new cable and new CSP for your provision , unless you intercepted the installation people and said it’s OK to use the existing CSP on your neighbours wall , they won’t object as it’s less work for them , although if small 4 Toby boxes putting two cable through a small toby isn’t strictly allowed .
I would take a look at the footpath outside your home to see what was installed.
