WA RETAINING WALL CASE - TACTICS

[SP3]

I started a court case to recover a cost share of a fence from the neighbour, who refused to pay . I am self represented. The neighbour ( who is represented by a lawyer ) counterclaimed, saying my retaining wall was defective and should be repaired/replaced.
I obtained an engineers report that found that the retaining wall was defective because the neighbour had undermined it with his house development.
My question is, should I update my initial statement of claim to include the repair of the retaining wall , now I have proof it was the neighbours' fault?
Or should I leave it as is in the hope that , if i win, I could still seek the cost of the retaining wall repair from the neighbour?
If I do update my initial statement of claim ,do I open myself up to a "thrown away " cost claim from the neighbour?

 

[Rod]

Up to you. If it was me I'd update my claim.

Why would 'throw away costs' apply? You are adding something new to an existing claim, not taking away part of your original claim.

 

[SP3]

Up to you. If it was me I'd update my claim.

Why would 'throw away costs' apply? You are adding something new to an existing claim, not taking away part of your original claim.

With this case, there are now 2 conflicting expert reports from both myself and the neighbor on what caused the retaining wall to fail. It was decided to engage a 3rd expert to review the first two expert reports and provide an opinion as to which one was right. The 3rd experts fee was to be pre- paid and shared equally by the two parties. That was about 18 months ago. Since then the neighbor has adopted a policy of endless delay, minimal communication, no cooperation, no negotiation and no engagement in finding resolution . I have recently obtained a quote from an expert to do the task. Can I lodge an application to the court seeking an order to compel the neighbor to pay a half share of the fee ?
If I am successful and the neighbor still refuses to cooperate or pay his fee share, what further steps can I take to progress the case?