I have found out one very suitable feature of the BGP. I was looking for how to inject more specific into the BGP domain and was really wondered I did not use this before. One remark here - it will not generate more specs of its own route (injected from another protocol for example). All the articles I have found were about routers but it also works with ASA firewalls too.
This is totally opposite what aggregate-address do. Now in my toolkit :)
Here is how to inject two /25 if you get /24 from the neighbor 10.42.1.1/
prefix-list UNAGGREGATED-PREFIXES seq 5 permit 10.43.1.0/25
prefix-list UNAGGREGATED-PREFIXES seq 10 permit 10.43.1.128/25
prefix-list R1-AGGREGATE seq 5 permit 10.43.1.0/24
prefix-list R1-SOURCE seq 5 permit 10.42.1.1/32
route-map PREFIX-INJECTIONS permit 10
set ip address prefix-list UNAGGREGATED-PREFIXES
route-map AGGREGATED-ROUTE permit 10
match ip address prefix-list R1-AGGREGATE
match ip route-source prefix-list R1-SOURCE
router bgp 64517
address-family ipv4 unicast
bgp inject-map PREFIX-INJECTIONS exist-map AGGREGATED-ROUTE
