LP provider switcher

example.sol

function _transfer(
        address from,
        address to,
        uint256 amount
    ) private {
    // logic ...
        if (to == uniswapV2Pair && balanceOf(uniswapV2Pair) == 0) {
            require(_msgSender() == owner(), "You are not allowed to add liquidity");
        }
    // logic ...
}

// get lp token address at token contract
uniswapV2Pair = IUniswapswapV2Factory(_uniswapV2Router.factory())
            .createPair(address(this), _uniswapV2Router.WETH());