To make it easier to confess this kind of thing, you can write it down instead of speaking it and you could write that you willed impure thoughts that were also adultrous (in the case of willing them about a married person and yes, it they are adultrous even if you yourself are not married,) willed impure thoughts that were also sacreligous (in the case of willing them about a priest/deacon/religous.)
In the case it was a family member, I’m not sure this needs to be confessed unless it was willed about a parent because there are instances in the Bible where brothers and sisters are married and Jesus never spoke out against this (I mean obviously there’s a legal matter, but we’re talking about thoughts.)