How to add more than one IdentityServer4 Authentication in my project

I added into my project IdentityServer4 and create my implementation of IExtensionGrantValidator. Also we have another project which can issue tokens which can be valid for our service. There is a scheme. How can I validate token in local Identity starage and External? Both of them were written by our teams. If I add

                .AddIdentityServerAuthentication(options =>
                {
                    options.SupportedTokens = SupportedTokens.Reference;
                    options.Authority = "http://localhost:5000";
                    options.RequireHttpsMetadata = false;
                    options.ApiName = "myApi";
                    options.ApiSecret = "userSecret";
                })

into my Startup.cs then token will be validate only in one service.