Method for high-pressure access through a multilateral junction

A method for accessing a well system, comprising:

• placing a multilateral junction proximate an intersection between a main wellbore and a lateral wellbore, the multilateral junction including;
• a y-block, the y-block including;
• a housing having a first end and a second opposing end;
• a single first bore extending into the housing from the first end, the single first bore defining a first centerline;
• and
• second and third separate bores extending into the housing and branching off from the single first bore, the second bore defining a second centerline and the third bore defining a third centerline;
• a mainbore leg coupled to the second bore and extending into the main wellbore;
• and
• a lateral bore leg coupled to the third bore and extending into the lateral wellbore;
• and
• selectively accessing at least one of the main wellbore or the lateral wellbore with a fracturing string through the y-block.