A pattern is read by considering the whole measure, the position of alif, and the preceding vowel rather than only the final spelling.
SingularPluralNotable change
خَادِعٌخَوَادِعُWāw in the plural pattern
خَالِدٌخَوَالِدُWāw in the plural pattern
A wāw appearing in a plural is not automatically a radical. Determine the root and pattern before explaining the changed form.