#2
Sepsidoscinis maculipennis Hendel, 1914 (Chloropidae). See the original description (Annls hist.-nat. Mus. nat. hung. 12: 247-248); also Mlynarek, 2018 (Zootaxa 4471 (1): 001-036, Figs 50-55, 57), Manual of Afrotropical Diptera, Vol. 3, 2021, Fig. 97
#4
That's apparently what is identified as a sepsid fly approaching the prey of a feeding thomisid spider and flollowing salticid spiders, photographed in Karnataka (India): Hill et al., 2020 - Kleptoparasitic flies and jumping spiders (Araneae: Salticidae) - Peckhamia 202.1, 1-7, Figs 2.2, 5;
https://peckhamia..._202.1.pdf