Hi Fiona - you should rely on the casework team's communication with you and seek legal advice as appropriate.
As you have an open application there's nothing we can assist with via the forum
The response re your still pending application sets out what might be possible but it's only with legal advice that you are likely to understand the legal nuances highlighted in that letter.
Our PG 24 -
Private trusts of land (PG24) - GOV.UK and PG 19 may be of wider assistance -
Notices, restrictions and protection of third-party interests (PG19) - GOV.UK but it is legal advice you require here as to what your legal rights/interest are.
If the interest to be protected is identical then one form can be used with both title numbers included. But you really do need legal advice as to what, if anything, you can apply for