SQL & PL/SQL :: Check For Those Ukeys With Multiple Eids

I want to check for those ukeys with multiple eids and different tds values ('ukey1' and 'ukey3' below), if the correspoding tds value in abdtab is null,so our query *should ignore 'ukey4' (multiple eids but same tds value), and ukey5 (not even mulltiple eids)*points to consider:

1. ukeys from aetab table should have multiple eids
2. for those records, go to abdtab and check if tds value is null or not, join condition for aetab and abdtab is

aetab.bkey = abdtab.addkey;
create table aetab(ukey varchar2(100),eid number, bkey varchar2(100), tds varchar2(100));
create table abdtab(tds varchar2(100), addkey varchar2(100));

insert into abdtab values (NULL, 'ukey1');
insert into abdtab values ('somevalukey3','ukey3');
insert into abdtab values('somevalukey4','ukey4');
insert into abdtab values('somevalukey5','ukey5');
[code]....