### Subposets of the Boolean lattice via Sage

Let $B_n$ be the Boolean lattice of a set with $n$ elements.
Is there a quick method via Sage to obtain all subposets $P$ of $B_n$ containing the empty set and having the property that with x in $P$ also the complement of the set x is in P and such that with x and y in P also the union of x and y is in P if x and y are ~~disjoint?~~

disjoint?
(probably this works only for small $n$ but $n \leq 6$ would already be interesting)
Thanks for any help