Vourneen,
First of all, both your pre-existing conditions DO NOT affect changing from one VHI plan to another. Hospital cover is identical so no waiting applies.
Regarding, the private hospital/private room cover, Parents and Kids Options plan covers a person upto the semi-private rate and the patient pays the difference. This cash shortfall could be 300+ extra per night depending on the private hospital involved. 100% tech charges means that the surgery is fully covered but the accommodation is covered upto a semi-private room and you pay the difference for a private room.
Plan PMI 42 15 has extra cover regarding a private room in a private hospital, the shortfall per night is just 50 euro compared to 300+ per night.
Again surgery is fully covered on plan PMI 42 15, upto semi private room and you pay 50 extra per night for a private room.
Now, as its extra cover, it is classed as an upgrade in cover, so this particular section would be subject to a 2 year waiting time for both of your pre-existing conditions.
You would still have the option of a private room in a private hospital for 300+ per night, Parents and Kids Options cover would apply until 2 year waiting is over.
You would have the same hospital cover as before otherwise, plus the extra day to day cover after the relevant waiting times are served, at the cheaper price.
For your sons, the 23 yr old would probably be better staying with VHI One Plan as he may require VHI International cover for his time abroad.
The 36 yr old could switch to Simply Connect with Laya if he wanted extra day to day cover for the same price as VHI one plan.
Hospital cover is the same for both plans.
Regards, Snowyb