The modal logic S4.2 with the characteristic axioms

4: $\square \alpha \rightarrow \square \square \alpha$

and

.2: $\lozenge \square \alpha \rightarrow \square \lozenge \alpha$

and

T: $\square \alpha \rightarrow \alpha$

is sound and complete for transitive, reflexive and connected frames. Such frames validate the closure principle

CP $\lozenge \square \alpha \wedge \lozenge \square \beta \rightarrow \diamond \square (\alpha \wedge \beta)$

Can someone help me with deriving CP in S4.2?