Update subnets with Incremental Deployment

I'm trying to update subnets with below ARM code to update it's private endpoint policy, enable service endpoint and delegate subnet to a service in Incremental mode. However when I run it, it remove the NSG/UDR on the subnets, I'm afraid it is also changing other subnet settings to their default value. How can I deploy this via ARM by only changing the specified configuration.

{
"apiVersion": "2017-05-10",
"name": "updatePrivateEndpointSubnet",
"type": "Microsoft.Resources/deployments",
"resourceGroup": "[parameters('vnetRG')]",
"properties": {
"mode": "Incremental",
"template": {
"$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"resources": [
{
"name": "[concat(parameters('vnetName'), '/', parameters('privateEndpointSubnet'))]",
"id": "[resourceId(parameters('vnetRG'), 'Microsoft.Network/virtualNetworks/subnets', parameters('vnetName'), parameters('privateEndpointSubnet'))]",
"properties": {
"addressPrefix": "[parameters('privateEndpointSubnetAddressPrefix')]",
"privateEndpointNetworkPolicies": "Disabled",
"privateLinkServiceNetworkPolicies": "Enabled"
},
"type": "Microsoft.Network/virtualNetworks/subnets",
"apiVersion": "2019-09-01"
}
]
}
}
},
{
"apiVersion": "2017-05-10",
"name": "updateVnetIntegrationSubnet",
"type": "Microsoft.Resources/deployments",
"resourceGroup": "[parameters('vnetRG')]",
"properties": {
"mode": "Incremental",
"template": {
"$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"resources": [
{
"name": "[concat(parameters('vnetName'), '/', parameters('vnetIntegrationSubnet'))]",
"id": "[resourceId(parameters('vnetRG'), 'Microsoft.Network/virtualNetworks/subnets', parameters('vnetName'), parameters('vnetIntegrationSubnet'))]",
"properties": {
"addressPrefix": "[parameters('vnetIntegrationSubnetAddressPrefix')]",
"serviceEndpoints": [
{
"service": "Microsoft.Storage"

}
],
"delegations": [
{
"name": "0",
"properties": {
"serviceName": "Microsoft.Web/serverfarms"
}
}
],
"privateEndpointNetworkPolicies": "Enabled",
"privateLinkServiceNetworkPolicies": "Enabled"
},
"type": "Microsoft.Network/virtualNetworks/subnets",
"apiVersion": "2019-09-01"
}
]
}
}
},

Start with the nested Microsoft.Resources/deployments snippets and the Microsoft.Network/virtualNetworks/subnets resources shown in the issue. Reproduce the incremental deployment behavior and compare the resulting subnet settings with the declared properties; done when the requested subnet changes no longer remove or reset unspecified NSG, UDR, or other settings.

Written by the indexing model from the issue text.