Consolidation

IndAS 103.54 "In general, an acquirer shall subsequently measure and account for assets acquired, liabilities assumed or incurred and equity instruments issued in a business combination in accordance with other applicable Ind ASs for those items, depending on their nature."

Now, that means Y ltd's PPE will be measured next year either at cost or revaluation model. What ever the amount arises from the valuation, it is recognised in the consolidated statements.

INDAS110.B88 "An entity includes the income and expenses of a subsidiary in the consolidated financial statements from the date it gains control until the date when the entity ceases to control the subsidiary. Income and expenses of the subsidiary are based on the amounts of the assets and liabilities recognised in the consolidated financial statements at the acquisition date. For example, depreciation expense recognised in the consolidated statement of profit and loss after the acquisition date is based on the fair values of the related depreciable assets recognised in the consolidated financial statements at the acquisition date."

So its like Parents assets + Subsidiary assets. Both of these company assets will be separately valued as per their subsequent measurements as per PPE standard and consolidate their values at fair value.