Don't panic I'm also still a Liberal Democrat.
There are already a number of members of the local Liberal Democrats who are also members of the Alliance Party.
I have never been a member of the Alliance Party, I only joined a political party when I went to University in Kingston, the first time I came back I wasn't aware that the Lib Dems existed locally, but also didn't want to get involved in local party politics at that time (late 90s) then I was working in the Civil Service. When I returned this time at the start for the sake of my job local party neutrality was a key factor while I worked for the Yes to Fairer Votes campaign. Then after that I felt that I could continue with my neutrality to work with whatever party was leading the way on liberal values. And yes that party wasn't always necessarily the Alliance Party.
However, in light of the events of this week. When there have been direct attacks on democracy following a vote in one council chamber which has erupted into violence, arson and other criminality I decided the time has come to stand and be counted. So I have joined the number of dual memberships.