I think I'm understanding you properly.
Okay, so what you want to do, is produce an sbp of a squad that has a squad_loadout_ext which includes only 1 ebp. It doesn't matter what this ebp is; it could be a rifleman or a sandbag.
In the sbp's action_apply_ext, you want to add a player_target_action calling a reinforcements_action which does not spawn random squads, with the loadout set to the two actual squads you wish to spawn.
Then, also in action_apply_ext, add a delay_action with a short delay (.2 will be fine), and then make_dead with "destroy" set to true.
Somewhat more detailed and intricate addendum:
To make your squads that spawn with reinforcements_action automatically proceed to your base, you'd need to make the action_apply_ext in the sbp call:
1) filter_action, target_info of has_all_in_list of has_unit_type "hq" and own. Which has an action_table of:
2) player_target_action, which has subactions of:
3) set_start_position_target_action, which has an action list of:
4) your reinforcements_action that calls the two squads.
This basically says "filter hq for its position, then set a rally point on it, and call the reinforcements to said rally point".
It works really good! thanks !!