And yes, we know it'll be chaotic at first going from zero to two kids but we know people with twins and have a good support network smile
Honestly, it’s nothing like having twins from birth. Adopting siblings is a whole different ball game. They will each have their own, usually competing, needs and will experience and process trauma differently from each other due to age, stage, time with birth parent etc. They may also be used to competing with each other for food, care, affection etc or one taking a protective role for the other (even from a very early age) which can really make parenting difficult.
I think folk often feel the earlier they’re with you the better, and there’s definitely some mileage in that children may be less exposed to trauma in the birth family, attachments may be potentially more secure etc. There is however a huge amount of uncertainty about their development and the degree to which this has been affected by their early and/or in utero experiences. It takes a huge amount of resilience to adopt siblings.
As a pp said, there’s also huge uncertainty about their legal status and practicalities of your relationship with them until permanence is agreed as part of their plan. For example, you would be expected to facilitate contact with the birth family on a regular basis, the children wouldn’t take your name, you would be referred to as their carers in formal meetings etc. Meanwhile you’re doing all the work of settling these children with you, in the full knowledge that they might not stay.
There are good things about foster to adopt, but in many ways it’s more uncertain that straight adoption.