i'm a bit drunk rn, may have problems with thought formulation
dying from benzos OD alone it's impossible:
LD50 Oral 1040 - 2500 mg/kg(diazepam). needed 31 to 75 thousands pills of 2mg for a person of 60kg weight
pfizer source: .. Diazepam Rat Oral LD 50 12600 mg/kg. here needed 378000 pills of 2mg for a person of 60kg weight
mixing benzos with opiates or alcohol is dangerous as it gives synergic CNS depression effect and chance of possible death due to respiratory failure, asphyxiation by vomit mass or circulatory collapse or any of these combined therefore drastically increases.
benzos+alcohol mixture deserved separate attention as it's very unreliable, first it comes from that both alcohol and benzos require very high doses to achieve lethal outcome, second individual reactions on alcohol and benzos are different from person to person, more different than for opiates, because most opiates are absolutely lethal at doses of 100mg to several grams, some successful suicides has been committed using this method ofc. but better not consider this seriously as persons who succeed might have predisposing factors like heart or lung disease.
so you should better to aim for benzos-opiate mix. as opiates are more toxic in case of overdose
there's list of celebrities who succeed:
https://en.wikipedia.org/wiki/List_of_deaths_from_drug_overdose_and_intoxication