Please describe what do you mean by linking A to B,C,D at first step.
Do you have separate table for newly registered and link it to ‘match candidates’ in other table? You can’t update more than one record per one automation step (without code), but you can use linking to ‘mark’ other matches for second automation.
It’s quite simple to do in 2 steps that way.
Other scenario - when you link A,B,C,D in a single table by ‘self-linking’, which doesn’t create reverse-links. Your goal can be accomplished as well, but you still need additional automation and use inter-table linking.
table1: Name1 | Link1 | lookup from t.2(name2)
table2: Name2 | his match | Link2
1st auto: triggered by A, (step2) find B,C,D in 1st table (step3) put their record IDs to field “link2” of t.2, and Name of A in field Name2
2nd auto: triggerred in table 1 when field Link1 is not empty (step2) create new record in table2, use data from triggered record Name1=>Name2, lookup=> his match (step 3) clear field Link1
thus, (step3) of 1st auto will cause update of 3 records in t.1, triggering three different runs of 2nd auto creating three new records.
i would also suggest to be careful, if you accidentally put something in Link2 in second automation, you can call ‘chain reaction’ that (if you have significant number of records) will hang your tables|automations for some time and quickly deplete your monthly limits (if any)