In folder BMS\Data\Campaign\Save you will find a file "f.ia" that you may alter to:
# Use BMS Editor to find Plane Units (!) and Weapon IDs
#####################################################
# Own plane (Unit Information) Example: F-16
# KF-16C-52
1 type
9 subtype
58 specific
#####################################################
#####################################################
# Weapon loadout: WeaponID (Weapon No.), WeaponAmount
#Loadout Hardpoint 0
#M61 - 510 rounds
623 W0
51 C0
#Loadout Hardpoint 1
# 1 x AIM120C
42 W1
1 C1
#Loadout Hardpoint 2
# 1 x AIM9M
#36 W2
# 1 x AIM9X
38 W2
1 C2
#Loadout Hardpoint 3
# 1 x AIM120C
42 W3
1 C3
#Loadout Hardpoint 4
#Loadout Hardpoint 5
# 300 Gal tank
301 W5
1 C5
#Loadout Hardpoint 6
#Loadout Hardpoint 7
# 1 x AIM120C
42 W7
1 C7
#Loadout Hardpoint 8 (empty on A-10)
# 1 x AIM9X
38 W8
1 C8
#Loadout Hardpoint 9
# 1 x AIM120B
#41 W9
# 1 x AIM120C
42 W9
1 C9
This will give you 4xAIM120C and 2xAIM9X
Numbers are weapon ID and wing # and the line below each is quantity and hardpoint# (I am not sure how to mix those)
for mudmoving you have the same style in a "m.ia" file.
Weapon ID can be found with F4Browse but if you need another missile I can get you the ID so you don't have to install F4Browse if you don't have it already.