TOPSwitch SMPS with component obscelesence issue

hello,

i am making an offline flyback smps (85-265VAC), which will comprise two isolated TOPSwitch flyback SMPS's.

This is because, amongst other reasons, there are two isolated outputs required, i.e. 30V (+/-10%) and 5V (+/- 4%).
The 5V rail power is from 170mW to 2W
the 36V rail power is a maximum of 36W (but most of the time will be between 2W and 12W)

It must be minimum 85% efficient when loaded above 1W

It must draw less than 500mW when the output load is 170mW.

This calls for two SMPS's , one for the 5V rail, and one for the 36V rail.
-the SMPS for the 36V rail will be shut down when in "standby" ("standby means the 5V rail is loaded with 170mW), since 36V is not needed in "standby".

(obviously these two smps's will share the same C(in) and EMI filter, FWB etc.

In order to cut costs, i wish to use a LNK302 to act as the smps controllers' power source.
I will use an off-the-shelf transformer for the 5V rail, in order to cut costs.

-The thing is, suppose that the off-the-shelf transformer goes obselete,
-i woul dthen have to select another off-the-shelf transformer, and re-arrange the circuitry a bit...........

-i presume that i would then need to treat the power supply as a whole new power supply, and put it through all of the approvals testing all over again? (eg EMI, vibration, hunidity, transient etc etc)