will show how to recover the one-parameter case from the two-parameter case. The case when one of $\lambda$ or $\Omega$ vanishes is trivial and it can be recovered from the above expressions just setting either $\lambda=0$ or $\Omega=0$. Let then consider the only other case, which arises when the two parameters $\lambda$ and $\Omega$ are not longer independent, e.g. $\Omega=\Omega(\lambda)$. Then the specific way of recovering the single parameter ($\lambda$) case will depend on the specific function $\Omega(\lambda)$. Here we illustrate the simplest case of a linear relation $\Omega = a \lambda$ ($a\neq 0$). To arrive to the one-parameter expansion (see [@BMMS; @SB; @BS]), we need to study the consequences of the dependence between the two parameters. We can do that by looking at the definitions of the operators $\cL_{(p,q)}$ in equations (\[operator10\]-\[operator04\]), and at their association with Lie derivative operators, described by equation (\[lieder\]). The result is a set of relations between the vector fields $\xi_{(p,q)}$ that can be summarized in the following relation: \_[(p,q)]{} = \_[(p+q,0)]{} . Then, rescaling the vector fields $\xi_{(p,0)}$ in the following way: $\xi_{(p,0)} \rightarrow (p+1)^{-1}\xi_{(p,0)}$, we arrive at exactly the same expansions as in the one-parameter case [@BMMS; @SB; @BS]. In the case 