Theres some ways to achieve that.
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You can peer both isp without Route Rule and VRF, then edit your bgp peer connection with different router-id (will go with different instance) and you will see + sign on routing table showing multipath.
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Also without vrf and Route Rule. You can add single dummy static route maybe 1.1.1.1/32 with multiple gateway to isp1 and isp2. Then edit both filter-in bgp to set gw 1.1.1.1; accept;. It will showing recursive and based multiple gateway, you achieve ecmp also.
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Wait until MikroTik supported BGP Equal Cost Multipath officialy