Existing FTTP to property but BT won't upgrade FTTC second line.

[Sapchild]

I already have a live BT FTTP service (900Mb) into our property and also have a separate older and live BT FTTC line running at 36Mb with a phone line. For some reason BT won't allow me to upgrade the second line to FTTP. (lots of family members and kids using broadband) We had FTTP installed last year, (driveway dug up, conduit installed etc.) It should be easy for them to pull another cable throught if that's what is needed anyway? Other FTTP providers seem fine with me switching (long out of contract) but I assume Openreach will still be needed for the install. 

[36ULW]

Every NAD Key is assigned only one FTTP Port due to capacity issues.

Openreach use GPON OLT’s, which uses a 32 Way Splitter. So basically that’s service for a Maximum of 32 Customers per Head End Port.

It may be possible to get a Second FTTP Circuit but that would most likely incur excess construction costs, which with FTTP could be in the thousands of pounds. 

[licquorice]

It doesn't need a separate fibre cable, it just needs a 2 port ONT to provide 2 services.

However, there are 2 obstacles.

First there may not be a spare channel on the PON.

Secondly there may be a restriction on more than one service per property.

I would have thought 900M would be sufficient, however big your household. 

[36ULW]

Openreach stopped providing Multiport ONT’s a few months ago.

https://www.thinkbroadband.com/news/no-more-multiport-ont-from-openreach-with-its-full-fibre-service...

[iniltous]

Other providers offering a switch simply arrange with Openreach to take over your existing service , so effectively you just connect the new providers router to the existing Openreach ONT on the appropriate date , Openreach are not needed for the installation, apart from remotely directing the traffic to and from you toward your new ISP  , not by visiting your address.
If you want a second service, unless an Alt Net is also available, you are stuck with FTTC until it’s withdrawn, or upgrade to 1.6Gb  offered by EE in some areas , BT may even  offer a penalty free migration to EE (as it’s a sister company) , it’s still only one FTTP service but faster than the aggregated 900Mb +36Mb services , but in truth you probably never get near the limit of your 900Mb service.

[WSH]

If it’s a matter of wanting the kids in a separate network, just create two separate subnets.  One for you, one for the kids.

Both will work over the same FTTP connection and, as people have said, 900Mb/s should be plenty fast enough to cope.