I'm struggling to setup a nested itemize with no blank line and several columns.

What I mean is something like

1. a) bla   c) bla

    b) bla   d) bla

The following MWE is my starting point

\starttext
\startitemize[n]
\item \blank[-line]
\startitemize[a,horizontal,two] [margin=2cm]
\item First
\item Second
\item Third
\item Fourth
\stopitemize
\item \blank[-line]
\startitemize[a,horizontal,columns,two]
\item First
\item Second
\item Third
\item Fourth
\stopitemize
\stopitemize
\stoptext

Thanks in advance