Perhaps can include an adoption system in the future. As we play the game, we realised that the easiest way to play is to not have children (cause they are expensive). Which the ancient Romans realised as well, that's why many would not have their own children and instead adopt them from their extended family trees. Like Julius Caesar adopting Octavian.
We will going forward - it'll tie in better with making the best use of your sisters' children as well. Right now, you do automatically adopt a promising young Roman if you die without heirs. Thank you for your patronage and for the suggestion!