I did a second test, this time with external and internal records.ini
Code:
\Test\Disk1\Setup.exe
\Test\Disk1\data1a.arc
\Test\Disk2\data1b.arc
\Test\Disk3\data1c.arc
\Test\Disk4\data1d.arc
\Test\Disk5\data1e.arc
\Test\Disk6\data1f.arc
\Test\Disk7\data1g.arc
[Record1]
Type=Split
Source={src}\data1a.arc
Output={app}\data1.arc
Disk=1
[Record2]
Type=Split
Source={src}\data1b.arc
Output={app}\data1.arc
Disk=2
[Record3]
Type=Split
Source={src}\data1c.arc
Output={app}\data1.arc
Disk=3
[Record4]
Type=Split
Source={src}\data1d.arc
Output={app}\data1.arc
Disk=4
[Record5]
Type=Split
Source={src}\data1e.arc
Output={app}\data1.arc
Disk=5
[Record6]
Type=Split
Source={src}\data1f.arc
Output={app}\data1.arc
Disk=6
[Record7]
Type=Split
Source={src}\data1g.arc
Output={app}\data1.arc
Disk=7
[Record8]
Type=Freearc_Split
Source={app}\data1.arc
Output={app}
Disk=7
It works just fine.
Splitted files were initially meant for put them into different folders, but it also work if you put all together into one folder. If you put all into one folder, don't forget to change the disk number inside records.ini.