We report recent progress in data analysis on the two point
correlation functions which will be prerequisite to obtain
semileptonic form factors for the $B_{(s)} \to D_{(s)}\ell\nu$
decays. We use a MILC HISQ ensemble for the measurement. We use the
HISQ action for light quarks, and the Oktay-Kronfeld (OK) action for
the heavy quarks ($b$ and $c$). We used a sequential Bayesian method
for the data analysis. Here we test the new fitting methodology of
Benjamin J.~Choi in a completely independent manner.