Enquiry: Medical-oriented migration agents?

Good morning!

I made an initial evaluation for my whole family to immigrate in New Zealand through NZ Shores agents. The plan is arranged (temporary work visas, then the residence) but there´s a medical issue concerning my youngest son which could mean the whole family being rejected. Although the services, contracts, and everything else about these agents is clear and I´m ok with their plan, I need to know if anybody has experience in medical issues through immigration and could give me some info.
Is there a medical-oriented migration agency, or at least some agengy that has more expertise in the subject? From the medical outcome or getting a medical waiver depends my whole family process, so I´d like to start it with the right agent.
I will find helpful any experience with medical issues, wether it´s a rejection or a succesful process.
Thanks in advance!!!!

I think if you can show you have the funds to cover the medical condition this may help.