Flavia Theodora - Who Made Her Coins?

Going back through my Roman coins, and I found my little AE4 of Theodora, and got to thinking, who made it?

Theodora became the wife of Constantius I in 293 when he divorced his wife Helena to seal a more political marriage. This move caused Constantine I to be sent away to the court of Diocletian, only to come back to prominence when he served as a general under his father. Constantine was reasonably friendly with his half-siblings upon becoming emperor, and granted some of them political offices during his reign. After his death in 337, the empire was split between his sons Constantine II, Constans, and Constantius II as co-emperors, and his nephew Delmatius as caesar. Another nephew Haniballianus held a small amount of territory as rex. Shortly after the death of Constantine, Delmatius and just about every other surviving member of the marriage between Constantius I and Theodora was put to death to consolidate power between the "true" heirs of Constantine. Constantius Gallus and Julian II were spared due to their youth.

That raises some questions. There are a few minor variations on a small AE4 coin featuring Theodora on the obverse. They all are of the same type, PIETAS ROMANA, with Pietas breastfeeding an infant. Traditionally, they are attributed to the time period 337-340, when Constantine's sons were co-emperors.

It just doesn't all add up. If they had just killed all of her children and grandchildren, why did they issue a coin praising her for her piety? I would suggest that the coins were made by Delmatius, but they were only minted at Trier, Rome, and Constantinople, none of which Delmatius had any authority over.

Both this and the "pagan" representation of Pietas makes me wonder if perhaps they were issued by Julian II, later in the 360s?