why don't you put the options/properties from the 2nd command line to the others in the first?
i think of something like this
CODE
start /wait msiexec /qn /i %SYSTEMDRIVE%\Install\openofficeorg20.msi ALLUSERS=1 SELECT_WORD=1 SELECT_EXCEL=1 SELECT_POWERPOINT=1 ADDLOCAL=gm_Root,gm_r_Files_2,gm_r_Files_3,gm_r_Files_4,gm_r_Files_5,gm_r_Files_6,gm_r_Files_7,gm_r_
Files_8,gm_r_Files_9,gm_r_Fonts_OOo_Hidden,gm_p_Wrt_Bin,gm_p_Wrt_Help,gm_p_Calc_Bin,gm_p_Calc_Help,g
m_p_Calc_Addins,gm_p_Impress_Bin,gm_p_Impress_Help,gm_o_Oo_English,gm_o_Winexplorerext
This should all be on one commandline. However, I haven't tested it. So you might want to get something like VirtualBox or VMware to test-drive this.
note: '/qn' sets the installer to be totally silent, '/qb' does show the progress-bar.