Question regarding Extras Cover churning for Orthodontics

Not sure if this is the place to get some better clarity regarding Extras cover churning. I am looking to get as much of the cost of braces covered. I've been quoted $8,400 over 20 months which brings us to $420/month. I'm 25+ and have served my 12 month waiting period for orthodontic cover. The fund I'm with now - Teachers Union Health - has a lifetime limit of $2,500 with no annual limit and 100% back on claims. I am eyeing a swap to GMHBA as their lifetime limit is slightly higher at $3,000 with an annual limit of $1,500 at 60% back on claims and also Defence Health as they have no lifetime limit on orthodontics but an annual limit of $1,000. GMHBA limits reset at the end of the calendar year while Defence Health limits reset at the EOFY.

Now for my plan - I want to start orthodontic treatment ASAP and I am thinking of:

1. Claiming the $2500 limit for braces cover with Teacher's Union Health. The $2,500 would cover about 6 months worth of treatment, taking me into 2026.

2. Swap Extras Cover to GMBHA and claim the additional $500 between Jan - June 2026. That should only take a couple of months with only getting 60% back on claims.

3a. Once the 2026-2027 Financial Year starts, I would swap to Defence Health and immediately claim the $1000 annual limit for orthodontics.

3b. This may be pressing my luck, but I was thinking of asking the orthodontist if they could stretch my repayment plan to 24 months which would take me to Aug 2027 and allowing me to claim another $1000 for orthodontics

Executing all steps up to 3a takes me to getting $4,000 of the $8,400 covered. 3b. takes me to $5,000.

I am aware Defence Health is restricted and I believe I meet one of the criteria to join.

Any and all advice is welcome