Well we need more events for specific characters, so ideas like then will always come in handy. Now that I think of it, she should really have some fun with Hope (the butcher knife girl).
Well you can always try and make conditional switch. If you have both Hope and Silvia (thought it would be good name as it sounds almost like salvia) it would have trigger event first time. Hope as your sister would say "welcome home sister" than she would notice Silvia and would ask who is she. You would answer that you are techniaclly her mother since you adopted her but you've thought it would be suitable for Hope to have same age relative to play. You would also suggest new found sisters how about trainning. During the trainning it would have appeared that Silvia is:
1) strong and resistant: you would order special heavy armor armor that would fit her small frame and warhammer. Even though warhammer would be as big as her or even bigger she wouldn't have troubles in using it.
2) fast and agile: prepare for trouble and make it double although in opposite to her sister she would have use elegant rapier instead 2 very sharp knives.
3) have really high potential in magic. Saddly when you would get answer from messanger you would be pissed. It seems some stupid age barrier do not allow wild talents in age of 8 study it so you've taken her education in own hand. It seems she has some really good connection with elements.
4) you would notice that during training that Hope got hurt but before you've come you would see Silvias hair glowing and wound on Hopes elbow would dissapear.
If she is strong she would learn rock smash and boulder toss. Rock smash would be single turget high dmg stun atack, Boulder toss would be Aoe medium dmg abillity.
If she is agile she would learn ripost and weapon art. Ripost stance would be self buff increasing her DEF and AGI and also reflecting high dose of physical dmg dealt to her - also it would provoke enemies to atack her, Weapon art High dmg single target hit with oneshot possibility.
If she is magic oriented she would have discover 4 enchanted version of arcane arrow (a.mat * 4 - b.mdf * 2 formula for norma aracane shot with variance of 20 and crit possibility, a.mat * 5 - b.mdf * 2 with variance of 25 + special effect + crit): Fire bolt, Ice spike, Lighting spear, Stalagmite. Fire would have chance to burn target, Ice spike would have chance to freeze target decreasing target MEV and EV (I hope it is evasion and magic evasion). Lighting spear shocking target lowering it's MDF, and Stalagmite having chance to stun target. Wepon of choice spear.
If she got healing abillities she would have Child god purge - outcry of divine power dealing low - high dmg to every enemy of the caster. This spell would have high dmg moddifier but also high variance - it can deal 1 dmg it can also deal 1k dmg. Will of child god - healing all allies for low or very high amount (again high variance spell). Weapon of choice divine magic catalyst (maybe you should make something like darksouls talismans and holy chimes to cast divine magic).
New ideas tomorrow - stay tuned, I hope you like my current ideas,
). If you helped elf she woulkd get fine from their previous owner and would askj you if you want to be her new master. If you had taken her to her old.family you would be paid with valuable gem (maybe rainbow quartz gem). BTW if you had become her new master you can even order her to become your meal - she would do it gladly as she decide to serve you from her own will which was kind experience in opposite to being slave.
)
) you would meet ill looking girl. Under better look you would notice she had stiched arm, leg - basically stiched zombie girl. Look on her face would be sad - she would tell you in short her story: