Hi,
Nobody replied this one. It's understandable. But I looked for this kind of answer. We can change the ordering simply by changing the arrows declaration order.
@startuml
(1_1) AS t11
(1_2) AS t12
(1_3) AS t13
(2_1) AS t21
(2_2) AS t22
(2_3) AS t23
:Actor: AS A
A --> t11
A --> t12
A --> t13
A ---> t23
A ---> t22
A ---> t21
@enduml
Can be closed.