Hello G.,
The `PlantUML online web server ` accepts only one diagram...
What are your usecases ?
And if you would like to combine multiple times, you must use sub-diagram, as:
@startuml
label l1 [
{{
participant component1
participant component2
component1->component2 : message
}}
]
label l2 [
{{
start
:test;
stop
}}
]
@enduml
If that can help,
Regards,
Th.