Quedos

Remember you don't have to have a top table at all.
the bridal party can mingle with other on the table - have seen it done before and worked really well
but having asked round the office ( we have a colleague or two getting married)
and this
'yes we can but the point of the top table is parents of the bride and groom, she is not my parent and never has been she is only in our familly because she is married to my dad. '

the consensus is

talk to Kitten its a big deal to her
then mum and dad only at the top table and they can like or lump its - for the reception they can sit together once the meal is over. You have ensured that she's not alone and with people she knows. Its your day and don't let anyone ruin for you

Gd luck you two