Congrats on completing the set @Paul! I'm excited for you - that was a terriffic deal on the Plotina, thanks entirely to it being misattributed as Agrippina II by the auction house! I only caught it because it's a die match to my own example:
Sadly, that isn't the end of the road if one wants to collect *all* of the Nerva-Antonine dynasty...
- Marciana, sister of Trajan (Pricey!)
- Divus Trajan Pater, Biological father of Trajan (doable)
- Matidia, niece of Trajan (Pricey!)
- Antinous, Hadrian's boy toy (Extremely pricey!)
- Galerius Antoninus, Antoninus Pius' biological son (Exceptionally rare)
- Domitia Lucilla, Marcus Aurelius' mommy (Only a few known examples)
- Annius Verus Caesar, younger brother of Commodus (Doable with patience)
And it is also worth noting that many consider the little stick figure babies on the many
Fecunditas / Pietas issues of Faustina II to be representative of her living children at the time....