We are interested to know if one of our family members who is an old senior from Romania can permanently live with us in the UK. Does Brexit impose any restrictions?
Free movement remains in place during the transition period. So as an EU citizen he can come and live in the UK as long as he arrives before the end of 2020.
If he wants to remain in the UK long term, he will need to apply to the EU settlement scheme. Initially he should be granted "pre-settled" status. He will then later need to apply again to get settled status once he has lived in the UK for 5 years.