Platform: Windows
ISP: Century Link
Type of Internet Connection: DSL
Internet Connection Speed: 25Mbits
Date & Time: 06:30 June 4th, 2019
Frequency: Always
Character Name: Chiaia
Race: Elvan
World: Asura
Main Job: WHM then BRD
Support Job: Brd then WHM
Area and Coordinates: NORG
Party or Solo: Both
NPC Name: N/A
Monster Name: N/A
Steps:
1. Switched to WHM/brd casted Valor Minuet (1) which caps some wheres in between 155 and 166 for +32 Attack. I naturally have 155 skill in both Singing and Wind Skill naked as a sub job. With or without using Marvelous Cheer I was only getting a bonus of +30 Att so it's not combining the 2 skills. Put on all magic skills +10 neck and I'd hit the cap of +32 Attack with or without Marvelous Cheer equipped.

2. Switched to BRD/whm but did the testing with Valor Minuet V which caps out at much higher skill Got similar results obviously the +Attack numbers are different because it caps much higher.

3. On both WHM/brd and BRD/whm Marvelous Cheer did not grant a 2nd Song.

So it neither grants a 2nd song be it main BRD or sub job BRD.
Nor does it combine singing and wind skill be it main BRD or sub BRD.