Hainault, who currently has 27 caps, will join Canada for their friendly against Trinidad and Tobago in Fort Lauderdale. Taylor (48 caps) and Watson (19) will be a part of Jamaica's friendly versus El Salvador ay RFK Stadium in Washington, D.C.
The final call-up, Boniek Garcia will join Honduras for their friendly against Boca Juniors in Miami. Boniek has been capped 67 times by Los Catrachos.
The Dynamo do not have any mid-week matches during these friendlies, so none of the players should miss any league matches. How much they'll factor in to Houston's match against the Crew on 8/19 will have to be seen. All four players will be in New York and available for Friday's match against the Red Bulls before traveling to their respective national team camps.
With all the game being held in the US, the extra travel will at least be limited.