  It is beneficial to calibrate the period Wesenheit metallicity relation
(PWZR) of Delta Cephei stars (DCEPs), i.e., classical Cepheids, using accurate
parallaxes of associated open clusters (OCs) from Gaia data release 3 (DR3). To
this aim, we obtain a total of 43 OC-DCEPs (including 33 fundamental mode, 9
first overtone mode, and 1 multimode DCEPs.) and calibrate the PWZR as
$W_G=(-3.356 \,\pm\, 0.033) \,(\log{P-1})+(-5.947 \,\pm\, 0.025)+(-0.285
\,\pm\, 0.064)[\textrm{Fe/H}]$. The concurrently obtained residual parallax
offset in OC, $zp = -4\pm5\,\mu\textrm{as}$, demonstrate the adequacy of the
parallax corrections within the magnitude range of OC member stars. By
comparing the field DCEPs' DR3 parallaxes with their photometric parallaxes
derived by our PWZR, we estimated the residual parallax offset in field DCEPs
as $zp = -15\pm3\,\mu\textrm{as}$. Using our PWZR, we estimate the distance
modulus of the Large Magellanic Cloud to be $18.482 \,\pm\, 0.040$ mag, which
aligns well with the most accurate published value obtained through geometric
methods.
