Hi @Sylvain_Che
Yes this is possible. I have applied additional BGP settings such as BFD, max-paths and MD5 authentication to the DNAC automated L3-handoff configuration using a template without any issues. Example template below. DNA Center does not overwrite these settings.
## Border Handoff Advanced Interface Configuration
interface Vlan3001
bfd interval 100 min_rx 100 multiplier 3
no bfd echo
## Border Handoff Advanced BGP Configuration
router bgp 65000
address-family ipv4 vrf corp_vn
neighbor 10.1.1.2 fall-over bfd
neighbor 10.1.1.2 password <password>
maximum-paths 2