Those terms do not relate to your actual biological age, rather than to the time span since one has joined the WingTsun Organization.
All terms listed are in direct lineage.
Your Si-Fu is written with a dash. Another Sifu is i.e. Sifu Jeff. The use of those terms is not a religious act but an asian tradition showing acknowledgement and gratefulness to the fact that WingTsun was being taught over the centuries on a individual basis within a family structure. 4.000 WingTsun Schools in 65 countries.