i would lie ds1 down in bed with a bottle of milk and then sit beside him in my rocking chair- either bfing or just cuddling ds2 and holding ds1's hand. sometimes we would all just drift off to sleep, or ds2 and i would gently sneak out once ds1 was asleep.
another good option is to take them both into your bed and bfeed the baby whilst the toddler snuggles up next to you. ds1 often used to 'spoon' me while i was bfing ds1. it was so cute!