you only need one godparent, and the same person can be the sponsor for both children
the child who had an emergency baptism should have had the rite completed at a later date–anointing etc. If that was not done, it can be done when the other child is baptized. Most dioceses consider age 8 to be over the age of reason so she would go through RCIA with others of her age and receive baptism, confirmation and first communion together at Easter. If there is no reason he cannot receive, your son could make his at the same time. They could probably be in the same preparation class if you ask and explain why.
talk to the pastor, and to the person he designates to coordinate the sacramental preparation.
yes plenty of families have similar issues and we try to work with families to arrange things best for all the children concerned and taking special needs into account. See the priest.
for example this year a middle school child has been placed in RCIA by her grandmother, who has become her legal guardian. At the same time the uncle who is an adult but functions at a 7-8 year old level is being prepared for first communion, which he will receive along with confirmation, at Easter when his niece is received into the Church. A family friend who introduced the family to me will be the sponsor for both, as the grandmother never knew her son was a candidate for sacraments until this friend sent her to us.
another family has an autistic teen who cannot manage regular CCD classes but is being instructed at home, assisted by his younger sister who is in confirmation class, so he is her “service project” and she is learning her own faith more deeply this way. They will be confirmed together, although he will not be receiving communion as there is a physical issue that prevents it at this time.
and we have several sets of siblings of different ages who are preparing for and will be receiving sacraments at the same time. We call RCIA “family program” for this reason, because we try to set it up so all the family members who need sacraments receive the preparation they need in a manner most convenient for all concerned (rather than attending multiple days and times during the week).
