  Composite quantum compounds (CQCs) have become an important avenue for the
investigation of inter-correlation between two distinct phenomenon in physics.
Topological superconductors, axion insulators etc. are few such CQCs which have
recently drawn tremendous attention in the community. Topological nontriviality
and Rashba spin physics are two different quantum phenomena but can be
intertwined within a CQC platform. In this letter, we present a general
symmetry based mechanism, supported by \textit{ab-initio} calculations to
achieve intertwined giant Rashba splitting and topological non-trivial states
simultaneously in a single crystalline system. Such co-existent properties can
further be tuned to achieve other rich phenomenon. We have achieved Rashba
splitting energy ($\Delta E$) and Rashba coefficient ($\alpha$) values as large
as 161 meV and 4.87 eV$\r{A}$ respectively in conjunction with Weyl semimetal
phase in KSnSb$_{0.625}$Bi$_{0.375}$. Interestingly, these values are even
larger than the values reported for widely studied topologically trivial Rashba
semiconductor BiTeI. The advantage of our present analysis is that one can
achieve various topological phases without compromising the Rashba parameters,
within this CQC platform.
